Make google API key configurable

Hey everyone,
I've already made the initial changes and tested locally.Now I'm preparing the fork and will push the changes shortly.

Update:
I have worked on this issue and created a Merge Request to make the Google API Key configurable through the theme settings.

🔹MR !4

Changes Implemented:

• Added google_maps_key to the theme settings schema.
• Created a UI field in Appearance > Guesthouse Lite Theme Settings.
• Ensured the key is retrievable via theme_get_setting('google_maps_key').

This allows users to configure the Google Maps API Key easily without modifying code.
Let me know if any improvements are needed!