Set up authorization solution evaluation matrix

[j08lue]

Our goal is to evaluate whether KeyCloak alone, only with configuration, can support all the authorization workflows VEDA requires or whether additional solutions that build on top of KeyCloak are needed or desirable.

We decided to create an evaluation matrix about:

1. Whether the solution in its current form (only with configuration) supports a workflow
2. Whether additional custom development by us is needed
3. What effort it would make to maintain the solution longer-term
4. How well the target solution supports the use case

Preferable is a community-maintained free and open source solution with as little customization as possible, with the default being vanilla KeyCloak (most recent stable version).

If that performs well on all workflows, great. If there are reasons to look beyond, we will have them well documented.

Acceptance criteria

• Created evaluation matrix in the docs of this repo