feat: allow keeping the git directory during builds

It may be desirable to keep the contents of the git directory for the build process. Certain build tools can extract extra information from the .git directory, and some workflows may require that the shipped artifact has the entire source code available locally for later usage.

plugins/git/functions

@@ -67,7 +67,10 @@ git_build_app_repo() {
   fi
 
   suppress_output env -u GIT_QUARANTINE_PATH git submodule update --init --recursive
-  find . -name .git -prune -exec rm -rf {} \; >/dev/null
+  local DOKKU_KEEP_GIT_DIR="$(fn-plugin-property-get "git" "$APP" "keep-git-dir" "")"
+  if [[ "$DOKKU_KEEP_GIT_DIR" != "true" ]]; then
+    find . -name .git -prune -exec rm -rf {} \; >/dev/null
+  fi
 
   if use_git_worktree; then
     pushd "$DOKKU_ROOT/$APP" >/dev/null