Remove HAL module from core and create a contrib project for it

Problem/Motivation

In #3049856: [policy] Mark HAL module as deprecated in D9 so it can be removed in D10 → we deprecated the HAL module with the intention to remove it from D9. This is the issue to do the actual removal.

Currently postponed on

#3263618: Deprecate HAL module →
#3264633: Remove \Drupal\layout_builder\QuickEditIntegration and refactor it so that quickedit contrib provides the integration with layout builder →

Proposed resolution

1. Find someone to volunteer to maintain HAL in contrib. We have had troubles finding a maintainer for HAL in core for a while.
2. Create a HAL module in contrib that users can update to seamlessly when upgrading to D9. We will also remove deprecations and BC layers as discussed in #3034062: Remove hal.module BC layers → .
3. Remove the code and the unused leftover dependencies (if any).

Remaining tasks

DONE. Hypermedia Application Language (HAL) → Contrib project created with maintainers larowlan, Spokje, bbrala
Test the contrib module
Remove the module from core

User interface changes

None.

API changes

None.

Data model changes

None.

Release notes snippet

The HAL module was introduced during the development of Drupal 8, but never received much traction in the decoupled scene due to the vague specification and issues with the implementation. As a result, few sites use HAL in production.Additionally, JSON:API in core offers a superset of features over HAL.

Therefore, HAL is deprecated in Drupal 9.4 and has been removed from Drupal 10.0. It is instead available as the HAL contributed project instead. If you need the functionality provided by HAL, read more on using the HAL contributed module → .