[PHP 8.4] Fixes for implicit nullability deprecation

[Ayesh]

Fixes all issues that emit deprecation notices on PHP 8.4 for implicit nullable parameter type declarations. Related to #20128. This is against the master branch while the other PR targets the 2.2 branch.

See:

• RFC
• PHP 8.4: Implicitly nullable parameter declarations deprecated

Q	A
Is bugfix?	✔️
New feature?	❌
Breaks BC?	❌
Fixed issues	N/A

[what-the-diff]

PR Summary

• Enhanced Code Clarity in Framework
  Nullability annotations were added to the 'trigger' method in the base component of our framework, resulting in improved code readability and maintainability.

• Database Active Query Improvement
  The viaTable and via methods in ActiveQuery & ActiveRelationTrait received nullability annotations. This helps developers quickly understand when a null value is expected and reduces potential errors and bugs.

• Mail System Code Quality Improvement
  We improved the robustness of the mail system by annotating the send method in our BaseMessage and MessageInterface with nullability, highlighting that these methods can handle null values.

• Improved Code Definition in Tests
  Numerous test files, such as FakePhp71Controller, ContainerTest, stubs/Alpha, and FakePhp7Controller, have been annotated for nullability on various parameters. This allows for better understanding of these tests since developers can now anticipate null values during execution.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 63.64%. Comparing base (ac1a5af) to head (da5f809).

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #20133      +/-   ##
============================================
- Coverage     64.82%   63.64%   -1.19%     
  Complexity    11376    11376              
============================================
  Files           429      429              
  Lines         37074    37073       -1     
============================================
- Hits          24034    23594     -440     
- Misses        13040    13479     +439     

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[samdark]

Thank you!

[Ayesh]

Thank you for triaging and coordinating this.