Make compatible with the Unity Package Manager and remove git submodule

[thestonefox]

Currently VRTK imports Zinnia into the project via a git submodule, which in turn includes the hard dependency of Malimbe.

There is some work to be done on Zinnia to make it a valid Unity package and remove the hard dependency of Malimbe.

When this happens it will break VRTK as there is a requirement to pull in the dependencies via a git submodule.

Moving forward, including VRTK will require including the package in the project manifest.

Zinnia ticket reference https://github.com/ExtendRealityLtd/Zinnia.Unity/issues/430

[thestonefox]

As each Prefab will be split out into its own repo eventually, I wonder if the easiest way forward right now is to just nest the Prefabs directory within a Runtime directory.

Runtime/
--Prefabs/

Then there only has to be 1 asmdef under runtime right now. In the future each repo will contain its own Runtime and asmdef.

[ExtendReality-Bot]

:tada: This issue has been resolved in version 4.0.0 :tada:

The release is available on:

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• v4.0.0
• GitHub release

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[bddckr]

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