Add Support for Marker Clustering

[JarrydLong]

Is your feature request related to a problem? Please describe.
Marker Clustering helps 'cluster' markers that are within close proximity from each other. This helps when a map has a large number of markers.

Describe the solution you'd like
Add support for marker clustering.

Describe alternatives you've considered
This will require changes to the main JS file as we can't do this with a recipe.

Additional context
https://github.com/googlemaps/js-markerclustererplus/blob/main/examples/simple_example.html
https://developers.google.com/maps/documentation/javascript/marker-clustering#adding-a-marker-clusterer

Relates to https://www.paidmembershipspro.com/forums/topic/action-filter-hooks-for-enabling-google-api-marker-clustering-on-membership-maps/ (Moderators only)