CI/CD - Perform testbuild using Github Actions

[dsilhavy]

Description

As part of a CI/CD workflow it would be nice to perform a testbuild for each pull request. That way we make sure that no breaking changes are introduced without performing a manual build each time.

[nlsdvl]

Added a git hook and started looking into github actions for building this repo:
5G-MAG/rt-xr-unity-player#5

Anyone looking forward to contribute to this repository is welcome to take this task on.
This should be implemented as part of supporting Android targets.

Created a separate ticket CI/CD - 5G-MAG/rt-xr-unity-player#21

[nlsdvl]

CI on the MAF API for media pipelines : https://github.com/5G-MAG/rt-xr-maf-native/pull/6/checks
CI on the Unity project, currently building : 5G-MAG/rt-xr-unity-player#23

These currently support win 64 builds.