Create a separate InitContext

Only a couple of these functions would be needed during initialization.
In the next couple commits ProcessContext will get a way to access
auxiliary IO, so this really had to be separated.

plugins/puberty_simulator/src/lib.rs

@@ -179,7 +179,7 @@ impl Plugin for PubertySimulator {
         &mut self,
         _bus_config: &BusConfig,
         _buffer_config: &BufferConfig,
-        context: &mut impl ProcessContext,
+        context: &mut impl InitContext,
     ) -> bool {
         // Planning with RustFFT is very fast, but it will still allocate we we'll plan all of the
         // FFTs we might need in advance