SQLite3Adapter now checks for views in table_exists? fixes: 14041
Updating Associations::Preloader docs

Much of the previous documentation introduced features new in 2011. This
commit refreshes it to provide clearer code examples and spends more
time describing the normal case (preloaded associations) and less time
describing the fallback.

[ci skip]
Roll back open transactions when the running thread is killed.
Default to sorting user's test cases for now

Goals:

1. Default to :random for newly generated applications
2. Default to :sorted for existing applications with a warning
3. Only show the warning once
4. Only show the warning if the app actually uses AS::TestCase

Fixes #16769
Do not memoize document_root_element in view tests

Memoizing will not make possible to assert the output of the view if it
is changed after the first assert_select call

Related with plataformatec/simple_form#1130 and rails/rails-dom-testing#15
Add docs for web-console to 4.2 Upgrade Guide [ci skip]
Merge pull request #16845 from todd/upgrade_guide_console_docs

Add docs for web-console to 4.2 Upgrade Guide
Remove extra 'has been' from the deprecation message

- [ci skip]
Merge pull request #16847 from prathamesh-sonpatki/kill-extra-has-been

Remove extra 'has been' from the deprecation message
Remove extra 'has been' from deprecation warning about asserting selectors

[ci skip]
Merge pull request #16848 from prathamesh-sonpatki/kill-extra-has-been

Remove extra 'has been' from deprecation warning about asserting selectors
Update upgrading guide about error handling in transactional callbacks

- Part of 16576
- [ci skip]
Merge pull request #16846 from prathamesh-sonpatki/document-error-handling-in-transactions-callbacks

Update upgrading guide about error handling in transactional callbacks [ci skip]
:scissors: "now" [ci skip]

minor fix for #16846
Remove extra newline from ActiveJob test template
[ci skip] change the line orientation on asset precompile page
Allow included modules to override association methods.

Closes #16684.

This is achieved by always generating `GeneratedAssociationMethods` when
`ActiveRecord::Base` is subclassed. When some of the included modules
of `ActiveRecord::Base` were reordered this behavior was broken as
`Core#initialize_generated_modules` was no longer called. Meaning that
the module was generated on first access.
Merge pull request #16850 from aditya-kapoor/correct-line

[ci skip] change the line orientation on asset precompile page
Merge pull request #16849 from y-yagi/patch-1

Remove extra newline from ActiveJob test template
introduce `connection.supports_views?` and basic view tests.

`AbstractAdapter#supports_views?` defaults to `false` so we have to turn it on
in adapter subclasses. Currently the flag only controls test execution.

/cc @yahonda