feat: create proxy:build-config command

Closes #4024

plugins/nginx-vhosts/help-functions

@@ -28,7 +28,6 @@ fn-help-content() {
   declare desc="return help content"
   cat <<help_content
     nginx:access-logs <app> [-t], Show the nginx access logs for an application (-t follows)
-    nginx:build-config <app>, (Re)builds nginx config for given app
     nginx:error-logs <app> [-t], Show the nginx error logs for an application (-t follows)
     nginx:report [<app>] [<flag>], Displays an nginx report for one or more apps
     nginx:set <app> <property> (<value>), Set or clear an nginx property for an app

plugins/nginx-vhosts/subcommands/build-config

@@ -8,6 +8,7 @@ cmd-nginx-build-config() {
   declare cmd="nginx:build-config"
   [[ "$1" == "$cmd" ]] && shift 1
   declare APP="$1"
+  dokku_log_warn "Deprecated: Please use proxy:build-config"
 
   [[ -z "$APP" ]] && dokku_log_fail "Please specify an app to run the command on"
   local PROXY_APP_TYPE