Adapt to draco 4.0.2 (Fix WebGL build for Unity 2021 and 2022)

[rasoulMrz]

As mentioned in issue #169, we have to use Draco version 4.x.x, in order to fix WebGL, builds on Unity 2021 and 2022. But it is also mentioned in the issue that if you simply remove the current version and install Draco 4.0.2 (e.x. using the installer provided in the GitHub repo) you will encounter build errors as the GLTFUtility is using methods with old signature. In order to fix this, you have to adapt the GLTFUtilityDracoLoader.cs to the new Draco API.

This pull request contains the adapted version of GLTFUtilityDracoLoader.cs and the old Draco plugin is also deleted from sources (you will need to install the new version as mentioned above).

[saszer]

Works well, hoping for a merge.

[EnigmaFactory]

This works great! Think this should get merged.