Migrate Mono APIs to CoreCLR-compatible APIs

[MiroBrodlovaUnityGit]

Purpose of PR

This PR replaces all instances of analyzer-highlighted Mono API calls with CoreCLR-compatible API calls in this repo, and is part of Epic SCP-1555.

Further Context

• Unity is steadily moving away from Mono to using CoreCLR.
• Epic SCP-1555 tracks this work.
• For more information, please visit #code-reload-safe-api-packages-migration 🙂

JIRA-ticket

• SCP-1555

Testing

Running the default job-suite. Please share if there are additional steps needed!

[unity-cla-assistant]

All committers have signed the CLA.

[MiroBrodlovaUnityGit]

Just double-checking if there's anything I should change/commit/add or any jobs I should kick off before this can land? :) Thanks in advance!