[Postgres]: Use schemas in-place of initialDumps

[shivaraj-bh]

Problem

initialDumps is always created under postgres database, which is not a desirable default behaviour when your dumps are intended for different database, like atlas_dev in nammayatri.

Solution

We already have schema module option to load a schema into a given database name. The schema module option already supports loading from either a file or all the .sql files in a folder.

The sql dumps in some cases can be scattered across folders, and hence we can rename schema to schemas and allow it.

Tagging @rsrohitsingh682 here as he had worked on initialDumps