Improve retrieval of properties from LOI documents

[rfontanarosa]

• query pagination
• query data instead of proto conversion
• promise.all/map instead of for (order is not important)
• select only necessary fields

[gino-m]

@rfontanarosa Is this draft PR still valid / working?

[rfontanarosa]

@rfontanarosa Is this draft PR still valid / working?

yes, but i have to add the changes merged in master. I'll do it once this (#2249) will be approved.