[meta] Modernize TMGM code

Problem/Motivation

TMGMT code is left behind as PHP modern development patterns.

Proposed resolution

• #3631457: Use modern square brackets array representation
• #3631468: Use modern PHP functions, operators
• #3631475: Autowiring for services
• #3631480: Use constructor property promotion
• #3631484: Improvements to plugin attributes definitions
• #3631487: Use ::class instead of hardcoded FQNs
• #3631490: Convert hook implementations to OOP
• #3631501: Make some class properties readonly
• #3631502: Strict type where possible
• #3631653: Fix static analysis failures
• #3631793: Deprecate procedural code
• #3632059: Use attributes in tests
• #3631795: Fix PHPCS
• #3631794: Make next minor, previous major, previous minor tests pass
• Conversion of routes to attributes (is this possible while keeping BC for Drupal < 11.4?)

Remaining tasks

Decide how to do the modernization: atomic (each plan item an issue) or all in a big MR It was decided to implement one by one

User interface changes

None.

API changes

None.

Data model changes

None.