Remove Copilot

This has been taking forever on Explorer's side (Node, why did you clone all of the NPM registry into one folder??) but in terms of Git there isn't really anything here.

Author: Lamparter

.gitignore

@@ -9,6 +9,7 @@
 **/PROJECT_MIGRATION_LOG.txt
 **/.pf/build/
 *.csproj.*.proj
+Riverside.Alliance.Components.Portal/
 
 # User-specific files
 *.rsuser