fix: php fixes from writing rules

[didroe]

Description

Fixes for PHP:

• Make elements in associative array initializers unanchored
• Improve usefulness of variable shape error message - this is encountered sometimes when a rule is invalid
• Handle both single and double quoted strings in patterns - these now match both kinds of strings in the code (for literals)
• Lookup variables in more places
• Update pattern match node and unanchored offsets to account for fixups
• Add more container types
• Fix string handling (applies to other languages also)

Checklist

• I've added test coverage that shows my fix or feature works as expected.
• I've updated or added documentation if required.
• I've included usage information in the description if CLI behavior was updated or added.
• PR title follows Conventional Commits format