Reject unknown collectgarbage options

[ashtonmeuser]

Simple fix for failing Test_Lua("tests-lua/errors.lua"). This is not a complete implementation of Lua GC and, similar to existing behaviour, largely ignores the GC option. However, it now throws for unexpected option strings.

[Copilot]

Pull request overview

Updates the Lua standard library surface to better match Lua’s error behavior by rejecting unknown collectgarbage option strings and adding a __gc metamethod entry for file handles.

Changes:

• Add validation for collectgarbage(option) to throw on unexpected option strings.
• Register a __gc metamethod on FileHandle metatables and implement a stub handler that errors when invoked without arguments.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
src/Lua/Standard/BasicLibrary.cs	Validates collectgarbage option strings against a known set and throws on invalid options.
src/Lua/Standard/FileHandle.cs	Adds __gc to the file handle metatable and introduces a GcFunction implementation.

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[ashtonmeuser]

This is a subset of #273. Focuses on just two failures encountered in errors.lua in the Lua test suite. @akeit0 feel free to close this if you'd prefer #273.

[akeit0]

Revert or reopen with improving collectgarbage with KnownCollectGarbageOptions only may be better.

[akeit0]

Thanks!