Added enqueue_at support for QueAdapter in ActiveJob

* Added inline job runner for Que in test/support
* Updated QueAdapter to support enqueue_at
Clarify that unknown keys will become HTML attrs

Docs for all the other form tag helpers in this
file already clarify this.

[ci skip]
Remove erroneous form_tag option docs

This is true of the first param (url_for_options),
not of the second options param which is being
documented here.

[ci skip]
Merge pull request #16648 from seuros/master

[ActiveJob] Add hook for test_framework
Merge pull request #16602 from thetron/active_job_que_enqueue_at_support

Added enqueue_at support for QueAdapter in ActiveJob
Merge pull request #16647 from tjschuck/form_for_doc_options

Documentation update for form_for options
Use zero-padding for number_to_rounded_converter
Merge pull request #16650 from zzak/fix-precision-number_to_rounded_converter

Use zero-padding for number_to_rounded_converter
Properly referencing AR::RecordNotFound in AJ guide rescuing example
Merge pull request #16655 from brocktimus/20140823_doco_change

Correct AR::RecordNotFound in AJ guide rescue example [ci skip]
Fix example code in Active Job guide [ci skip]
Merge pull request #16659 from y-yagi/patch-4

Fix example code in Active Job guide [ci skip]
Don't trim excess whitespace in pg #columns_for_distinct

Fixes #16623 introduced by https://github.com/rails/rails/commit/3d5a2019bcccc6fb01bee4811ca669f4383edb51
Fix guide anchor generation logic.

This could use in any translation because it's not limited to `[^a-z0-9]`.

Verify after this change, all guides still have same anchors.

[Robin Dupret & Juanito Fatas]
Merge pull request #16649 from Agis-/pg-columns-for-distinct

Fix postgresql adapter #columns_for_distinct trimming whitespace it shouldn't
CHANGELOG & improvements to #16649

* Require either FIRST or LAST qualifier for "NULLS ..."
* Require whitespace before "NULLS ..."
Merge pull request #16667 from JuanitoFatas/patch/anchor-generation

Fix guide anchor generation logic.
Raise ActiveJob::SerializationError when cannot serialize job arguments
Merge pull request #16671 from cristianbica/aj-raise-serialization-error

Raise ActiveJob::SerializationError when cannot serialize job arguments
[ActiveJob] Add activesupport as dependency [ci skip]