No support for multiple host configuration

[wpatrik14]

Libpq library supports multiple host configuration (https://www.postgresql.org/docs/12/libpq-connect.html), however it's not supported in pg/pg-native library.

The pg/pg-native library should enable to define a connection string towards libpq like this:
postgresql://host1:1234,host2:5678/mydatabase?target_session_attrs=read-write

Currently it's not possible due to the limitation of pg/pg-native library...