Add some target fields and move some things around (#3879)

In preparation for putting proxy code in the api package this creates some necessary fields in the target output and it pre-moves credential parsing and proxy handshake code to their new places. This will make the diff for the actual proxy code move quite a bit smaller.

Co-authored-by: Johan Brandhorst-Satzkorn <johan.brandhorst@gmail.com>

.copywrite.hcl

@@ -22,5 +22,6 @@ project {
     "internal/proto/plugin/**",
     "internal/proto/controller/custom_options/**", 
     "internal/proto/controller/api/**",
+    "internal/proto/worker/proxy/v1/**",
   ]
 }