refactor: combine both clone and sync commands

Using a single command will allow users to not have to worry about the workflow they use to setup or update a given app.

plugins/git/subcommands/sync

@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+source "$PLUGIN_AVAILABLE_PATH/git/internal-functions"
+set -eo pipefail
+[[ $DOKKU_TRACE ]] && set -x
+
+cmd-git-sync "$@"