Fixes incorrect spelling of `action_on_unpermitted_parameters` in guide

See `actionpack/test/controller/parameters/raise_on_unpermitted_params_test.rb`

Closes #12293. Strong parameters should permit nested number as key.

Migrations Guide: Add semicolon to sentences before code block [ci skip]

Thread safety fixes

Removed where_values_hash from AR::NullRelation

Cleanup identitymap logger from LogSubscriber

From now on only the `[]=` method is allowed to modify the internal states hashes.

TS::Cache#compute_if_absent guarantees that only a single thread will get to execute the provided block for a given key.

Also renaming ivar @odd_or_even to @odd

Migrations Guide: Fix line length [ci skip]

In order to build associated records for owners which has not been saved
need to get where values to use as default attributes.
But for new record owner uses `ActiveRecord::NullRelation` which
override `where_values_hash` to return empty hash stub.

`where_values_hash` is not used to invoke any sql query, but good to
build others chains (even will be never executed) like:

```ruby
  post          = Post.new
  admin_comment = post.admin_comments.build

  assert_equal 'Admin', admin_comment.author
```

Closes #11376, #11676, #11675

side of a hm:t association along with preloading.

Fixed grammatical typo in configuring.md guide.

Getting Started Guide: Fix code container in Chapter 5.2 [ci-skip]

Getting Started Guide: Update sentence in Chapter 5.8 [ci-skip]

Remove HelperyTestHelper not used in any test

Add new line after create action on CommentsController code example [ci skip]

Adds template dependencies rake task from cache_digests gem.

This adds the rake tasks `cache_digests:dependencies` and `cache_digests:nested_dependencies` from `cache_digests` gem.

[ci skip] Update scaffold output and change some words.

Scaffold output: add jbuilder, update timestamp (edge guide!)

Add some file breadcrumb (comment) to help reader find files.

Improve readability by adding some command outputs.

Thanks for great help from @senny.

Getting Started Guide: post.rb -> Post [ci skip]

[ci skip] escape unintended url in docs

added "id: false" to HABTM join table example [ci skip]

Getting Started Guide: posts_controller -> PostsController [ci skip]

[ci skip] Add missing periods in active_record_basics.md.