Remove is_a? check when ignoring tables

Technically changes the API, as it will allow any object which responds
to `===`. Personally, I think this is more flexible.
Adding simple docs for ActionDispatch::Flash::FlashHash#to_session_value
adding nodoc to private methods
Do not rescue Exception in ParamsParser

Unlike ShowExceptions or PublicExceptions, ParamsParser shouldn't
transform exceptions like Interrupt and NoMemoryError into ParserError.
Fixing wrong link in 'Ruby on Rails 3.0 Release Notes' [ci skip]
Merge pull request #17767 from javiervidal/fixing_documentation

Fixing wrong link in 'Ruby on Rails 3.0 Release Notes' [ci skip]
do not trigger AR lazy load hook before initializers ran.

[Rafael Mendonça França & Yves Senn]

This require caused the `active_record.set_configs` initializer to
run immediately, before `config/initializers`. This means that setting any
configuration on `Rails.application.config.active_record` inside of
an initializer had no effects when rails was loaded through `rake`.

Introduced by #6518

/cc @rafaelfranca
bring back `db:test:prepare`.

This reverts deprecations added in #13528.
The task is brought back for two reasons:
  1. Give plugins a way to hook into the test database initialization process
  2. Give the user a way to force a test database synchronization

While `test:prepare` is still a dependency of every test task, `db:test:prepare`
no longer hooks into it. This means that `test:prepare` runs before the schema
is synchronized. Plugins, which insert data can now hook into `db:test:prepare`.

The automatic schema maintenance can't detect when a migration is rolled-back,
modified and reapplied. In this case the user has to fall back to `db:test:prepare`
to force the synchronization to happen.
CSS fix for the router visualizer
Setting an association replaces records with the same id in memory

The records weren't being replaced since equality in Active Record is
defined in terms of `id` only. It is reasonable to expect that the
references would be replaced in memory, even if no queries are actually
executed. This change did not appear to affect any other parts of the
code base. I chose not to execute callbacks since we're not actually
modifying the association in a way that will be persisted.

Fixes #17730
Merge pull request #17739 from rails/bring_back_db_test_prepare

bring back `db:test:prepare`.
Remove Web Console /console references in the guides
Merge pull request #17769 from gsamokovarov/remove-slash-console-references

Remove Web Console /console references in the guides
Local vars should exist in partials for falsy `:object:` values too

c67005f221f102fe2caca231027d9b11cf630484 made the local var in partials
available only if what passed to `:object` was truthy.

For example this would not make the local variable `foo` available inside the
partial:

    render partial: 'foo', object: false

Fixes #17373.
Move PG float quoting to the correct location

Not sure how we missed this case when we moved everything else to the
`_quote` method.
Merge pull request #17768 from bruno-/router-visualizer-css-fix

Small fix for the router visualizer
Use released rails-dom-testing
Use released arel
Merge pull request #17733 from yuki24/do-not-rescue-exception-in-params-parser

Do not rescue Exception in ActionDispatch::ParamsParser
Merge pull request #17771 from agis-/issue-17373

Local vars should exist in partials for falsy `:object:` values too