feat: add ability to initialize a git repository out of band

This is useful in contexts where the repository directory may be created and interacted with via git-http-backend or other methods of updating a repository.

plugins/git/subcommands/default

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
+source "$PLUGIN_AVAILABLE_PATH/git/internal-functions"
+
+cmd-git-help "git:help"