Add GeoSite and GeoSiteStatus grape entities

What does this MR do and why?

This is the first part of implementation for #369140

Add GeoSite and GeoSiteStatus grape entities to use them for a new geo_sites API endpoint

These entities will be used in the next MR where geo_sites endpoint is added

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

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Related to #369140