create setup_git script

docker/php/scripts/setup_git.sh

@@ -0,0 +1,36 @@
+#!/bin/sh
+
+setup_git() {
+  echo "Setting up Git..."
+
+  GIT_URL="https://oauth2:${GIT_TOKEN}@${BACKEND_GIT_REPO}"
+  BRANCH="${BACKEND_GIT_BRANCH:-main}"
+  FORCE_CLONE="${FORCE_CLONE:-false}"
+
+  git config --global --add safe.directory "$APP_DIR"
+
+  if [ ! -d "$APP_DIR/.git" ]; then
+      echo "Cloning repo..."
+      git clone -b "$BRANCH" "$GIT_URL" "$APP_DIR"
+  else
+      echo "Updating repo..."
+      cd "$APP_DIR"
+      CURRENT_BRANCH=$(run git rev-parse --abbrev-ref HEAD)
+
+      if [ "$CURRENT_BRANCH" = "$BRANCH" ]; then
+          run git fetch origin
+          run git reset --hard origin/"$CURRENT_BRANCH"
+      else
+          if [ "$FORCE_CLONE" = "true" ]; then
+              rm -rf "$APP_DIR"
+              mkdir -p "$APP_DIR"
+              git clone -b "$BRANCH" "$GIT_URL" "$APP_DIR"
+          else
+              run git fetch origin
+              run git reset --hard origin/"$BRANCH"
+          fi
+      fi
+  fi
+
+  cd "$APP_DIR"
+}