Support multi-collection in partition-filter

[MohamedHamouGisaia]

No description provided.

[alainbodiguel]

Proposed implementation is to pass the partition filter as a map <collection name, filter>, e.g.:
partition-filter: {"mycollection1": {"f":[[{"field":"city","op":"eq","value":"Bordeaux"}]]}}
The previous format is still supported and is a fallback in case the partition filter cannot be parsed as the new format, e.g.:
partition-filter: {"f":[[{"field":"city","op":"eq","value":"Bordeaux"}]]}