Move Wasmtime for .NET to the Wasmtime repo.

This moves the Wasmtime for .NET implementation to the Wasmtime repo.

Wasmtime for .NET is a binding of the Wasmtime API for use in .NET.

crates/misc/dotnet/examples/memory/memory.wat

@@ -0,0 +1,12 @@
+(module
+  (type $t0 (func (param i32 i32)))
+  (import "" "log" (func $.log (type $t0)))
+  (memory (export "mem") 1 2)
+  (data (i32.const 0) "Hello World")
+  (func $run
+    i32.const 0
+    i32.const 11
+    call $.log
+  )
+  (export "run" (func $run))
+)