Allow explicit configuration of TTRPC address

Previously the TTRPC address was generated as "<GRPC address>.ttrpc".
This change now allows explicit configuration of the TTRPC address, with
the default still being the old format if no value is specified.

As part of this change, a new configuration section is added for TTRPC
listener options.

Signed-off-by: Kevin Parsons <kevpar@microsoft.com>

plugin/context.go

@@ -28,12 +28,13 @@ import (
 
 // InitContext is used for plugin inititalization
 type InitContext struct {
-	Context context.Context
-	Root    string
-	State   string
-	Config  interface{}
-	Address string
-	Events  *exchange.Exchange
+	Context      context.Context
+	Root         string
+	State        string
+	Config       interface{}
+	Address      string
+	TTRPCAddress string
+	Events       *exchange.Exchange
 
 	Meta *Meta // plugins can fill in metadata at init.