feat(hana): add support for hana

[adriantankodev]

Description of your changes

My colleague @mirzakopic and I added support for the SAP HANA database. Following resources are available:

• Schemas
• Users
• Usergroups
• Roles

This of course allows other resources to be added later on. We have also added only the basic resource parameters for now, but it is extendable.

I have:

• [x] Read and followed Crossplane's contribution process.
• [x] Run make reviewable to ensure this PR is ready for review.

How has this code been tested

In order to increase code isolation, we decided to separate controller and client logic. Therefore tests for both are also separated.

[Duologic]

My initial feeling is that this would fit better in separate provider (perhaps one dedicated and/or owned by SAP?), WDYT?

[adriantankodev]

We have decided to create a separate provider as per your suggestion, so that it can be maintained directly by SAP. Thank you for the recommendation, I will go ahead and close the PR.