Add Vendor filter to requests on MAP

Add a layer or filter to the MAP that allows a user to filter requests shown on the map by vendor.

In some organizations dispatchers need to view all vendors so the users are not associated to a vender in their user profile. These users still want to filter the map to see specific vendor requests on the map rather than all requests. The request is to add a filter like we have for assets or alternatively like we have for request lines that would allow an admin or unvendored user to filter the requests shown on the map by vendor.