Add new oc-build project structure

[Qonfused]

As per https://github.com/Qonfused/ASUS-ZenBook-Pro-Duo-15-UX581-Hackintosh/issues/1, this PR adds a declarative build system for different UX481FA/FL models. This uses OC-Build to build the EFI directory, including versioning for external or local configs, ssdts, kexts, etc. This enables easier collaboration and documentation between different zenbook duo laptops/models (across different repositories/forks), addressing Qonfused/ASUS-ZenBook-Pro-Duo-15-UX581-Hackintosh#1.

Current Tasks

• [x] Add oc-build submodule
• Split into new PR:
  • [x] Add CI process for testing or building on each commit/semver bump
  • [x] Add CI process for building forked or patched kexts
  • [x] Add CI process for validating EFI build structure
• [x] Include project-specific documentation on running build scripts
• [x] Create a shared base/template config between UX481FA and UX481FL models.

[Qonfused]

This is considered stable for building on Linux and (tested on Ubuntu 20.05.05 LTS and openSUSE Tumbleweed) and on macOS (all versions supported). I've also tested builds using the same Linux distro versions using both wsl1 + wsl2 kernels on Windows 10 Enterprise LTSC (21H2, build 19044.2604) and the latest Windows 10 Pro and 11 Pro public builds.

With this PR, this repository will no longer store a built EFI folder (to avoid merge conflicts), which will require users to either manually run build scripts locally, or to use a built EFI from CI artifacts or releases. This is currently pending testing and verifying a manual build pipeline (although this should be reserved for a separate PR).