Fix unexpected select_tag delete behavior when include_blank is present

Don't round off subseconds unless necessary

Allow symbol (i.e. quoted identifier) as safe SQL string

[documentation][ci skip] stringify_keys and symbolize_keys have stable results.

The initializer receives `nil` for these options when no cofigurations were given:
https://github.com/rails/rails/blob/v6.0.0.rc1/activerecord/lib/active_record/railtie.rb#L91-L97

Change comments

[ci skip]

Wrap ActionView cache expiry in a mutex

 Bump Gemfile entry jbuilder version

Remove compatibility module from docs [ci skip]

[CI skip] Put :nodoc: on method that raises NoMethodError

Testing the result of `capture_sql` is fragile, it is due to whether
SCHEMA SQLs are executed or not depends on whether schema cache is
filled or not.

https://buildkite.com/rails/rails/builds/61248#a5b9dc59-ff0c-40c0-b56e-0895662fbc4c/993-1004
https://buildkite.com/rails/rails/builds/61248#1157b389-f2c7-4554-b6e5-a37624a0e74a/996-1005

I've confirmed all `capture_sql` use cases in our code base, all cases
won't expect SCHEMA SQLs are included.

```
% git grep -n capture_sql
test/cases/associations/belongs_to_associations_test.rb:202:    sql = capture_sql { comment.post }
test/cases/associations/belongs_to_associations_test.rb:204:    assert_not_equal sql, capture_sql { comment.post }
test/cases/associations/has_many_associations_test.rb:169:    sql = capture_sql { post.comments.to_a }
test/cases/associations/has_many_associations_test.rb:171:    assert_not_equal sql, capture_sql { post.comments.to_a }
test/cases/associations/has_many_associations_test.rb:276:    expected_sql = capture_sql { author.thinking_posts.delete_all }
test/cases/associations/has_many_associations_test.rb:281:    loaded_sql = capture_sql { author.thinking_posts.delete_all }
test/cases/associations/has_many_associations_test.rb:289:    expected_sql = capture_sql { author.posts.delete_all }
test/cases/associations/has_many_associations_test.rb:294:    loaded_sql = capture_sql { author.posts.delete_all }
test/cases/associations/left_outer_join_association_test.rb:22:      queries = capture_sql do
test/cases/associations/left_outer_join_association_test.rb:49:    queries = capture_sql { Author.left_outer_joins(:posts).to_a }
test/cases/associations/left_outer_join_association_test.rb:54:    queries = capture_sql { Author.joins(:posts).left_outer_joins(:posts).to_a }
test/cases/associations/left_outer_join_association_test.rb:60:    queries = capture_sql { Author.left_outer_joins({}).to_a }
test/cases/associations/left_outer_join_association_test.rb:65:    queries = capture_sql { Author.left_outer_joins([]).to_a }
test/cases/associations/left_outer_join_association_test.rb:78:    queries = capture_sql { Author.left_outer_joins(:essays).to_a }
test/cases/associations_test.rb:384:    log = capture_sql do
test/cases/associations_test.rb:399:    log = capture_sql do
test/cases/associations_test.rb:414:    log = capture_sql do
test/cases/associations_test.rb:429:    log = capture_sql do
test/cases/associations_test.rb:444:    log = capture_sql do
test/cases/associations_test.rb:459:    log = capture_sql do
test/cases/reflection_test.rb:307:    expected_sql = capture_sql { hotel.recipes.to_a }
test/cases/reflection_test.rb:312:    loaded_sql = capture_sql { hotel.recipes.to_a }
test/cases/relation_test.rb:212:      queries = capture_sql { Author.joins(:posts).merge(Post.joins(:comments)).to_a }
test/cases/relation_test.rb:232:      queries = capture_sql { Post.joins(:author, :categorizations).merge(Author.select(:id)).merge(categorizations_with_authors).to_a }
test/cases/relation_test.rb:347:      log = capture_sql do
test/cases/scoping/relation_scoping_test.rb:146:      log = capture_sql do
test/cases/scoping/relation_scoping_test.rb:159:    log = capture_sql do
test/cases/test_case.rb:33:    def capture_sql
test/cases/test_case.rb:41:      capture_sql { yield }
```

Fall back to type casting from the connection adapter

Return parameters enumerator from transform_keys/!

Implicit through table joins should be appeared before user supplied joins

Fix that an ActiveRecord::RecordNotUnique error would be raised when saving rich-text content with the same file attached multiple times.

typo change

Fix: DummyCompiler embeds invalid YAML content

Fix database loading when ERB is single line ternary

Backport 378dd7a4.

https://github.com/rails/rails/blob/65bdd6ad085a02b976cd36f135c2a5ffb522e5a0/activesupport/CHANGELOG.md

Fix eager loading associations with string joins not to raise NoMethodError

To avoid word wrap in the rendered guide.

Don't track implicit `touch` mutation

Update the sqlite db yaml template to match other templates and mention proper supported version

According to https://www.npmjs.com/.

Only build middleware proxy when instrumentating

Hide malformed parameters from error page

fixes #29947

Use params_valid? helper method to replace using instance variable

Should attempt `committed!`/`rolledback!` to all enrolled records in the transaction

The virtual attributes(`attachment` and `rich_text`) can't set value
with `fill_in`. So avoid using it. Once #35885 is merged, will be
modified to use it.

Also, add checking attachment attached or not for avoiding
`DelegationError` when attachment didn't attach.

Backport release notes to 6-0-stable