Action Cable: Defer starting connection monitor until a connection is opened

add `scaffold_stylesheet` method to guide [ci skip]

`scaffold_stylesheet` was added in #20479.

Action Cable: Establish WebSocket connection when first subscription is created

* More intention revealing than connecting on the first call to Connection#send
* Fixes that calls to Connection#send would attempt to open a connection when the WebSocket's state is CONNECTING

Forgot to update the documentation on the line just above the one
I was changing in 49331322. Well done, Kasper 👍

`ActionDispatch::SSL` redirects all HTTP requests to HTTPS, not just some.
The `constrain_to` option inverts this, so it sounds like the middleware
only handles a few requests, rather than the majority with a few routes to
opt out of the redirect.

Renaming to `exclude` matches this intent more closely.

Since f6e48148 was written we've made collection caching explicit.

Thus the documentation is outdated and needs a rewrite.

Support faye-websocket + EventMachine as an option

Closes #23934.

This is a forward port of ac832a43

Previously the scope of all associations with extensions were wrapped in
an instance dependent proc. This made it impossible to preload such
associations.

Change 'a HTTP' to 'an HTTP' [ci skip]

Niceify the dynamic routes deprecation messages

Change 'a HTML' to 'an HTML' [ci skip]

ConnectionMonitor is once again notified of disconnect

Follow-up to #23980.

- Fix grammar: "be remove" -> "be removed".

- Wrap lines at 80 chars.

Lurvely ;-)

Changed behaviour of timestamps helper by create_table migration generator [ci skip]

Fix a small template misrender in ActiveRecord::Persistence

See the end of [this] page.

[ci skip]

[this]: http://edgeapi.rubyonrails.org/classes/ActiveRecord/Persistence/ClassMethods.html#method-i-create

Deprecate `{insert|update|delete}_sql` in `DatabaseStatements`

This reverts changes made to integration tests in PR #23807.
The issue happens when using capybara with a driver that needs to start a
server in a separate thread like (poltergeist, selenium, etc).
Both threads the capybara server one and the test thread end running
syncronize over the interlock.

[ci skip] Add `bundle exec` for ActiveRecord unit tests

Fix description in cookies_serializer.rb being corrupted by gsub when updating

Fix typo in app_generator_test.rb

Fix typo in implicit_render

Remove not needed `exec_insert` in mysql2 adapter

 [ci skip] Use rails routes instead of rake routes in inspector test …

Accept channel identifiers with no backslashes/escaping

Fixes #22675

Allow channel identifiers and also data with no backslahes/escaping to be accepted by
the subscription storer.