vdk-plugins: support multiple database of the same type based on config subsections

[DeltaMichael]

Overview

For the following config, we should initialise multiple instances of the same database type. Each database should also register an ingester.

[vdk]
;some default trino config

[vdk.test_trino]
;some test trino config

[vdk.prod_trino]
;some prod trino config

This should also work with multiple databases, e.g.

[vdk]
;some oracle config

[vdk.oracle_test]
;some test oracle config

[vdk.test_trino]
;some test trino config

[vdk.prod_trino]
;some prod trino config

This case should be supported as well.

[vdk]
;some oracle config
;some trino config

[vdk.test]
;some test trino config
;some test oracle config

Suggested implementation

Acceptance criteria

The following plugins support multiple DBs of the same type (or separate tickets are opened for each plugin)

1. vdk-impala
2. vdk-trino
3. vdk-oracle