Chore: Modernize code using Rector

[RikudouSage]

Description

Modernizes the code using automated tools. Most commonly adds the PHP 8.3 #[Override] attribute. The attribute checks at compile time that the method is indeed overriding something and throws an error if it's not.

Other changes include:

• all global namespace classes are imported for consistency
• anonymous functions have been changed to short closures where applicable
• get_class() function call has been replaced with static ::class
• unused caught exception variables have been removed
• the Stringable interface is now implemented explicitly instead of implicitly

Note that all of this will be automatically reversed when releasing for older versions.

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[sighphyre]

LGTM