[Feature] Add SQL Data Source

[msoroka]

Originally created by LemonMind and TorqIT on Data Importer Extension.

All explained in attached docs.

[mattamon]

Hey @msoroka

Unfortunately the static analysis failed, could you please recheck your code and fix the tests.

[mattamon]

Hey @msoroka are you still working on this? It seems like a pretty cool feature, but with failing tests we cannot merge it.

Could you give me a quick comment, that you are going to fix this? Otherwise I will close the PR in a week. If you still want this, we can reopen the PR anytime then.

[msoroka]

@mattamon Yes, I'll do it till end of this week.

[mattamon]

@mattamon Yes, I'll do it till end of this week.

Awesome thank you!

[msoroka]

@mattamon Done