GD Place Fields for MLS

[Stiofan]

If a GD CPT has MLS enabled then the custom Fields under CPT > Settings > Custom FIelds should show MLS specific fields and auto add the main ones when enabling the setting on the CPT.

(should we hide all other field types and replace only with MLS ones?)

We will need to create the most common fields from the MLS, we may be able to reuse the property fields but we need to change the field keys so we can map these tot he MLS field keys.

Let's discuss this before you start this one.