Previously if a dynamic source returned a symbol such as :self it
would be converted to a string implicity, e.g:

  policy.default_src -> { :self }

would generate the header:

  Content-Security-Policy: default-src self

and now it generates:

  Content-Security-Policy: default-src 'self'

Remove extra call `remove_file` on `rails new` with `--skip_action_cable`

Rename event variable

Remove yarn's files from `.gitignore` template

There is no need to remove this file since the line below
removes entire directory in which that file is placed.

Merge pull request #34277 from bogdanvlviv/remove-javascripts-javascripts_engine-options-for-generators

Remove `javascripts` and `javascript_engine` options for generators

Remove `:javascript` from `Rails::PluginBuilder::PASSTHROUGH_OPTIONS`

It is unused since #33079

`--javascript` option was removed by 42198064

Webpacker already does it,
see https://github.com/rails/webpacker/blob/895d2cfc15eda2edae9e667c642a02523d958f53/lib/install/template.rb#L25-L33

I also opened PR https://github.com/rails/webpacker/pull/1765 in order
to make it add `/yarn-error.log` file too.

* Fix assertions of auto-generated ActiveStorage JS

Since #33079

* Correct message on the `assert_equal` failure

Related to #33079

* Test ActionCable's js files

This commit adds `app/javascript/channels/consumer.js`, and
`app/javascript/channels/index.js` to `DEFAULT_APP_FILES` in order
to assert their existance in `test_skeleton_is_created`.

Related to #33079

* Assert no match `javascript_pack_tag` in `application.html.erb`

Since #33079 `rails new` generates `application.html.erb` file
with `javascript_pack_tag` instead of `javascript_include_tag`.

Note that there some tests that asserting no matching
`javascript_include_tag` in the `application.html.erb` file
for newly generated rails plugins.
It is related to #34009 and shouldn't be changed right now.

Reduce string allocations in read/write_attribute

Improve variable naming by renaming from `e` to `event`.

The arguments to rename this are:
* The naming `e` is usually a convention used for exceptions.
* No other method in this class uses the naming `e`. All other
methods are using `event`.

When `attr_name` is passed as a symbol, it's currently converted to a
string by `attribute_alias?`, and potentially also `attribute_alias`,
as well as by the `read_attribute`/`write_attribute` method itself.

By converting `attr_name` to a string up front, the extra allocations
related to attribute aliases can be avoided.

Add message to exception in datetime type

Improve layout of Rails Guides index

Since #29294, `mattr_acessor` uses kwargs for `instance_reader`,
`instance_writer`, and `instance_accessor` options.

`thread_mattr_accessor` and `config_accessor` also take the same
options, so let's maintain these options handles the same.

Remove unnecessary escape character

`ruby -ractive_support/core_ext/range/conversions.rb -ep` dies with uninitialized constant ActiveSupport

If use `run_generator` to run the generator, `--skip-webpack-install`
is specified automatically.
https://github.com/rails/rails/blob/3101a4136bd62787e252d2658eee23001036fa0f/railties/lib/rails/generators/testing/behaviour.rb#L71

However, when executing the generator independently (for example, to use
stub), `webpacker:install` was executed.
Since this includes `yarn install`, it should be avoided in unnecessary
testing.

The previous version wasn’t matching the Rails Guides logo source file
listed at https://github.com/rails/homepage/blob/master/materials/rails_guides_logo.psd
somehow. It was also a GIF when an 8-bit PNG results in a smaller file (2KB vs 4KB) which
should be just as widely compatible with browsers.

And that’s just for the 1x version. I added a new 2x version for “retina” or high-density
displays and a CSS @media query to progressively enhance with this high density
version of the logo. I’ve ensured that this query is supported across browsers by
using vendor-specific versions when necessary. See:
https://caniuse.com/#feat=css-media-resolution

[ci skip]

The names are only used in the Guides Index overlay and several of them are
longer than they need to be.

For example “Ruby on Rails” is mentioned over and over again in the Release
Notes section although these are obviously all Rails versions we’re listing.

There’s a Maintenance Policy category with a Maintenance Policy article which
is redundant. Policies makes much more sense as a category.

Similarly, Contributing to Ruby on Rails is both a category and an article.
“Contributions” is a better category title. “Ruby on Rails Guides Guidelines” is
a gigantic mouthful. We are *in* the Rails Guides, we don’t need to specify
what guides we’re talking about here.

As a final added advantage, all of these shortenings make the index much easier
to parse in order to find an article.

[ci skip]

This notably allows us to tile each category without pushing the page down vertically
as much as we previously did on any viewport wider than mobile sizes.

It also means we can fit more guides which will become useful in the future since
we have several new guides in the work.

Finally the new layout allows three clearly distinct columns to emerge:
- Start Here and Rails basics: Models, Views, Controllers, Other Components
- Digging Deeper, Extending Rails, Contributing, Maintenance
- Release Notes

Having Release Notes shoot back up to the top of the third column is great
because that makes finding the latest released version and its associated
release notes much easier without having to scroll down a bunch.

[ci skip]

Add guides section on verbose query logs to Debugging

Since this is a useful tool in debugging it made sense to document
its existence and usage, especially in the console where it's disabled
by default.

[ci skip]

If the dev option is specified, Gemfile contains gem which specifies GitHub.
This will take time to execute, so should avoid it in unnecessary tests.

Make AJ integration tests work in CI

Since `@mutex.synchronize` is enforced in the `ensure_connection!` method,
there is no need to do so on the caller side.
https://github.com/jondot/sneakers/blob/c1b47f9c5d5a95da728bbe1700795790e4efbb12/lib/sneakers/publisher.rb#L22-L26

Due to this, `ThreadError(deadlock; recursive locking)` has occurred.

Also, replace the authentication setting. This is necessary for using
`psql` with PostgreSQL 10.
Ref: https://github.com/travis-ci/travis-ci/issues/9624#issuecomment-389537036

Fix typo in testing guide