refactor: move all port management code to standalone ports plugin

This change makes interacting with port mappings more clear - folks might previously set the port mapping to the proxy type or vice-versa.

The existing proxy:ports* commands still exist but will show a deprecation warning for a single minor release.

plugins/proxy/.gitignore

@@ -6,4 +6,4 @@
 /install
 /post-*
 /report
-!/proxy-configure-ports
+