Sync to upstream/release/524

[zeux]

• Improve type mismatch errors for classes defined in different modules
• Non-strict type inference now automatically infers function return types, similarly to strict mode
• Improve output of luau-analyze —annotate for arrays and for loops
• Make bytecode compiler ~5% faster by reducing temporary allocations
• Fix GCC9 warnings in CMake builds
• When new optimization level 2 is used (-O2 in CLI), bytecode compiler now unrolls short loops when profitable
• Improve incremental GC pacing to make GC workload more even
• Reduce the pace of sweeping during GC (this can make GC cycles a bit longer but reduces the frame time impact of GC in sweep stage)