Unity Apple Silicon (M1 arm64) support for Substance plugin
Can we get an ETA on when the Substance.Engine.bundle and libsubstance_link.dylib will be updated with arm64 (Apple Silicon) support?
Expected:
```
file Substance.Engine.bundle/Contents/MacOS/Substance.Engine
Substance.Engine.bundle/Contents/MacOS/Substance.Engine: Mach-O 64-bit bundle with 2 architectures: [x86_64] [arm64]
```
Actual:
```
$ file Substance.Engine.bundle/Contents/MacOS/Substance.Engine
Substance.Engine.bundle/Contents/MacOS/Substance.Engine: Mach-O 64-bit bundle x86_64
```
