Add script for applying the offline-mode to the current branch (#9951)

* Add script for applying the `offline-mode` branch to the current branch
* Add `--reverse` flag

scripts/apply_offline_mode.sh

@@ -0,0 +1,25 @@
+#!/bin/bash
+#####
+# This script applies the changes from the `offline-mode` branch in the `internetarchive/openlibrary` repo.
+# These changes will mock or otherwise prevent API calls to Internet Archive, resulting in a better
+# developer experience when IA is down.
+#####
+
+reverse=''
+
+# Parse command-line arguments
+while [[ $# -gt 0 ]]; do
+    case "$1" in
+        --reverse)
+            reverse='--reverse'
+            shift
+            ;;
+        *)
+            # Handle other arguments or show usage
+            echo "Unknown option: $1"
+            exit 1
+            ;;
+    esac
+done
+
+curl "https://github.com/internetarchive/openlibrary/compare/master...offline-mode.patch" | git apply $reverse