Independent, multi platform, includes licensing module

This release contains the following features:

• Re-implement license activation as part of this action
• Also implement returning of license as part of this action
• Effectively allow multiple Unity versions and platforms
• Fixed misleading explanation in readme (thanks to @Jibbajabbafic)

Fixes

Fixes for docker container ran from different repository

• #9 Fix build path
• #10 Always use relative path to action runner workspace

Multiple platform support 🎉

This opens up support for all platforms that are supported by @GabLeRoux docker images.

Special thanks to @umar-ahmed for coming up with this solution.

Self contained

Build is now better self contained;

• Build script has been extracted into the root of the project and is better documented
• Any licensing code has been removed in favour of the activation action
• Old code has been cleaned up where necessary

Unity - Builder

Build Unity projects for different platforms.