Expose `queries` for `AssociationQueryValue` and `PolymorphicArrayValue`

So we shouldn't claim they're there, even when asked explicitly.

Remove duplicated `delivery_method` definition

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use formatted number as schema version

Extract `construct_relation_for_exists` in `FinderMethods`

To ease to customize a relation for `exists?`.

It's been retired; all contributions now come in via PRs.

Calling fixture accessor method with no arguments returns all fixtures rather than empty array

A long-standing bug has been fixed in Rails 5.1 by @pixeltrix
See https://github.com/rails/rails/blame/5-1-stable/actionpack/CHANGELOG.md#L52-L64

This PR updates the guides accordingly.

Before:
<img width="799" alt="before" src="https://cloud.githubusercontent.com/assets/10076/24809105/4ec7066c-1b73-11e7-98c6-c709c3465306.png">

After:
<img width="799" alt="after" src="https://cloud.githubusercontent.com/assets/10076/24809109/50b21188-1b73-11e7-8a1a-32c3d0ed512a.png">

Passing in no arguments to the dynamic fixture accessor method returns all fixtures, not an empty array.

`ActionMailer::Base.delivery_method` is already defined in
https://github.com/rails/rails/blob/master/actionmailer/test/parameterized_test.rb#L13

Fix edge guides for Active Record callbacks

Fix `warning: extra states are no longer copied`

Fix `warning: already initialized constant HashWithIndifferentAccessTest::HashWithIndifferentAccess`

Remove duplicated "test" prefix

Fix `warning: already initialized constant HashWithIndifferentAccessTest::HashWithIndifferentAccess`

Caused since #28607.

I came up against this while dealing with a misconfigured server. The
browser was setting the Origin header to "https://example.com", but the
Rails app returned "http://example.com" from request.base_url (because
it was failing to detect that HTTPS was used).

This caused verify_authenticity_token to fail, but the message in the
log was "Can't verify CSRF token", which is confusing because the
failure had nothing to do with the CSRF token sent in the request. This
made it very hard to identify the issue, so hopefully this will make it
more obvious for the next person.

Ignore AR tests of index comment when using Oracle

Use appropriate type to `header` option

The `header` option checks only whether it is specified or not.
https://github.com/rails/rails/blob/e8c33349bfabca28996ac74d344d69c7aaffec50/railties/lib/rails/commands/dbconsole/dbconsole_command.rb#L52

https://bugs.ruby-lang.org/issues/13239

Don't highlight code in anchorlink [ci skip]

Minor fix to #28662

Downplay links in Guides headers

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