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/crisp/src/lib.rs

@@ -315,7 +315,7 @@ impl Plugin for Crisp {
         &mut self,
         bus_config: &BusConfig,
         buffer_config: &BufferConfig,
-        _context: &mut impl ProcessContext,
+        _context: &mut impl InitContext,
     ) -> bool {
         nih_debug_assert_eq!(bus_config.num_input_channels, NUM_CHANNELS);
         nih_debug_assert_eq!(bus_config.num_output_channels, NUM_CHANNELS);