Prefer `@connection.abandon_results!` than `@connection.next_result while @connection.more_results?`

These are internally used only.

[ci skip]

Correct capitalization of "Rails" in guide text

[ci skip]

correction to #31755 as per https://github.com/rails/rails/pull/31755#discussion_r165819798

Improve test for TaggedLogging "keeps each tag in their own thread"

These classes are internally used only.

Fix build failures on Travis

Removed "private" generators from command list.

Appropriate way to handle encrypted command is by `bin/rails credentials` and
`bin/rails encrypted`

It was displayed on `bin/rails generate` command:
```
Please choose a generator below.

Rails:
  application_record
  assets
  channel
  controller
  encrypted_file
  encryption_key_file
  generator
  ...
```

Allow ActiveStorage::Blob#service_url to pass addition options to service.url

I'm not sure cause, but due to the influence of `gem clean`, the expected
gem seems not to be installed correctly.
In order to avoid a test failure due to this, I fixed that `gem clean` not be executed.
Ref: https://github.com/travis-ci/travis-ci/issues/2518#issuecomment-121168856

This is a workaround. If Travis fixes something, please revert this.

* PERF: Recover marshaling dump/load performance

This performance regression which is described in #30680 was caused by
f0ddf87e due to force materialized `LazyAttributeHash`.

Since 95b86e57, default proc has been removed in the class, so it is no
longer needed that force materialized.

Avoiding force materialized will recover marshaling dump/load
performance.

Benchmark:

https://gist.github.com/blimmer/1360ea51cd3147bae8aeb7c6d09bff17

Before:

```
it took 0.6248569069430232 seconds to unmarshal the objects

Total allocated: 38681544 bytes (530060 objects)

allocated memory by class
-----------------------------------
  12138848  Hash
  10542384  String
   7920000  ActiveModel::Attribute::Uninitialized
   5600000  ActiveModel::Attribute::FromDatabase
   1200000  Foo
    880000  ActiveModel::LazyAttributeHash
    400000  ActiveModel::AttributeSet
        80  Integer
        72  ActiveRecord::ConnectionAdapters::SQLite3Adapter::SQLite3Integer
        40  ActiveModel::Type::String
        40  ActiveRecord::Type::DateTime
        40  Object
        40  Range

allocated objects by class
-----------------------------------
    250052  String
    110000  ActiveModel::Attribute::Uninitialized
     70001  Hash
     70000  ActiveModel::Attribute::FromDatabase
     10000  ActiveModel::AttributeSet
     10000  ActiveModel::LazyAttributeHash
     10000  Foo
         2  Integer
         1  ActiveModel::Type::String
         1  ActiveRecord::ConnectionAdapters::SQLite3Adapter::SQLite3Integer
         1  ActiveRecord::Type::DateTime
         1  Object
         1  Range
```

After:

```
it took 0.1660824950085953 seconds to unmarshal the objects

Total allocated: 13883811 bytes (220090 objects)

allocated memory by class
-----------------------------------
   5743371  String
   4940008  Hash
   1200000  Foo
    880000  ActiveModel::LazyAttributeHash
    720000  Array
    400000  ActiveModel::AttributeSet
        80  ActiveModel::Attribute::FromDatabase
        80  Integer
        72  ActiveRecord::ConnectionAdapters::SQLite3Adapter::SQLite3Integer
        40  ActiveModel::Type::String
        40  ActiveModel::Type::Value
        40  ActiveRecord::Type::DateTime
        40  Object
        40  Range

allocated objects by class
-----------------------------------
    130077  String
     50004  Hash
     10000  ActiveModel::AttributeSet
     10000  ActiveModel::LazyAttributeHash
     10000  Array
     10000  Foo
         2  Integer
         1  ActiveModel::Attribute::FromDatabase
         1  ActiveModel::Type::String
         1  ActiveModel::Type::Value
         1  ActiveRecord::ConnectionAdapters::SQLite3Adapter::SQLite3Integer
         1  ActiveRecord::Type::DateTime
         1  Object
         1  Range
```

Fixes #30680.

* Keep the `@delegate_hash` to avoid to lose any mutations that have been made to the record

Add changelog entry for #31844

Because there have some service needs more parameters for file URL:

https://www.alibabacloud.com/help/doc-detail/44687.htm

```rb
class AliyunService < Service
  def url(key, options = {})
    image_process = options[:oss_process] || "image/resize,w_800"
    "http://image-demo.oss-cn-hangzhou.aliyuncs.com/example.jpg?x-oss-process=#{image_process}"
  end
end
```

Use case:

```erb
<%= image_tag @user.avatar.service_url(oss_process: "image/resize,m_fill,h_100,w_100" %>
```

ActiveStorage: use the full class name for the JSON coder

`JSON` constant defined.

For example when using the `representable` gem: https://github.com/trailblazer/representable/issues/224

Update to latest rubies (2.2.9, 2.3.8 and 2.4.3) on Travis CI.

Consistent behavior for session and cookies with to_h and to_hash method

This reverts commit ac74e2c5, reversing
changes made to ffdb0613.

Fix `as` attribute value for preload link

`as` attribute value should be `style` for stylesheet preload link

See https://w3c.github.io/preload/#as-attribute

Because the master branch is already 6.0.

Fix typo

:tada::tada::tada:

Disable CSP by default

Before this patch, to be able to use webpacker and webconsole we were
defining an used default in the script-src policy. White we don't
implement the automatic nonce approach defined in
https://github.com/rails/rails/issues/31689 it is better to not have any
default configuration in Rails 5.2.

Add ContentSecurityPolicy to list of middleware

Document in the guides the new middleware added in #31162
[ci skip]

Update rails-ujs readme