feat(core,admin,testing-tools): core and admin tests

[sdimitris]

Introducing unit testing in core rpc services and admin using jest.

Fix: add 'config' prefix to '/modules' excluded route on Auth.middleware

• [x] Bugfix
• [x] Feature
• [ ] Code style update
• [ ] Refactor
• [ ] Build-related changes
• [ ] Other (please describe)

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

The PR fulfills these requirements:

• [x] It's submitted to the main branch
• [ ] When resolving a specific issue, it's referenced in the PR's description (e.g. fix #xxx, where "xxx" is the issue number)