Add Balta Test into CI & plpgsql_check into the repo - ideally into CICD pipelines

[lsulak]

Background

As we are increasingly using SQL (and pl/pgSQL), it might be a good idea to be more strict / have enforced or semi-encforced standards about our SQL code. This tool seems to be covering a lot of such needs: https://github.com/okbob/plpgsql_check/.

Also, add a CI check for the Balta tests so that it's all automatic and mandatory.

Currently we are testing our database functions with Balta: https://github.com/AbsaOSS/balta but we don't know what is our code coverage. Also, it might be good to perform some sort of static check code analysis (linting etc) on our SQL code.

The goal of this ticket is to include this tool into the project so that it's convenient and brings value for us.