Scopes + memory groundwork

[dphfox]

Partially implements #269. This PR introduces some groundwork for future memory management changes, and introduces basic support for the 'scoped' memory management pattern (https://fluff.blog/2023/08/30/the-next-ten-years-beyond-maids.html, https://github.com/dphfox/scoped).

• Move all memory management utilities into a dedicated Memory folder
• Rename cleanup to doCleanup for consistency (Fusion.cleanup should be renamed #237)
• Add destroy methods to all objects
• Add type information for destroy methods on objects
• Add cleanup tables as first parameters to all constructors
• Warn when scopes mismatch for things expected to have the same lifetime
• Implement scoped() syntax sugar for cleanup tables w/ constructor methods
• Generate inner scopes for state objects
• Ensure type checking mostly passes for additions, and note where it does not currently work so it can be targeted for future PRs
• Update unit tests
• Update API reference
• Update examples
• Update tutorials

[dphfox]

I think it'd be useful to pull in concepts from #220 for the backend implementation of the For objects. This won't be exposed to users yet - and it probably wouldn't be the final implementation because of #205 - but it'll be useful for tidying up those rat's nests and ensuring they have consistent destruction and memory management.

[dphfox]

Working on debugging the unified internal For implementation now.

[dphfox]

Now disposing of unused processors at the right time :)

[dphfox]

New For object implementations are now passing unit tests.