Convert Build Extensions to Wren Language

[mwasplund]

By converting to Wren we gain a lot of benefits and only a few drawbacks.

1. Hosting environment is able to create cleaner runtime environment with 1st class modules to interface with extensions.
2. Hosting environment is fully sandboxed, preventing build extension from accessing environment to cause issues.
3. No longer require dotnet sdk as a dependency unless building dotnet code!!!!!!

Downside: The biggest drawback is that Wren is a dynamically typed language which has caused a lot of runtime errors during migration that could have been caught with a static type system.