Some Mac support for Unity/Mono

[AlexKnauth]

This PR depends on #92 for V1Cattrs support, and replaces the old #53.

This adds Mac support for Unity/Mono V1, V1Cattrs, and V2. More V3 offsets could be added in the future after testing with a V3 game: my best educated guess at the V3 offsets is here: https://github.com/AlexKnauth/asr/tree/mono-4-v3

The Mac SceneManager support works without needing std or alloc.

The Mac Mono support needs alloc, but not std.

[AlexKnauth]

The macho::symbols iterator function still needs work.

It currently works for Hollow Knight 1.2.2.1 and 1.5.78, but not 1.4.3.2 on Mac.

Something is wrong with finding the symbol table and string table in memory.

A previous version that used the filesystem for the symbol table and string table, was able to work just fine. (I think)

[AlexKnauth]

After macho symbols: scan_macho_pages, it can finally attach to Hollow Knight Mac version 1432, which it couldn't do before.

[mitchell-merry]

That commit also makes it work for Cuphead, which wasn't working before!

For future readers, there was a bunch of discussion in the speedrun tool development discord about that, starting from here: https://discord.com/channels/144133978759233536/705023265860616223/1412084787820101773