Add OPAProperties to structure properties

[ali-jalaal]

Implements #21

[anderseknert]

Thank you! Looks like a solid imrovement to me. This is backwards compatible, right? Anything we need to the docs, or update? Looks like some tests are failing, so that'd be good to look into.

[ali-jalaal]

Hi @anderseknert, thanks for your review.

This is backwards compatible, right?

Yes, I suppose these changes are backward compatible since public constructors/methods of OPAAuthorizationManager are kept as before and behavior should be the same.

Anything we need to the docs, or update?

I'd suggest that we can update the docs after implementing #22 since after that we could use the features of auto-configuration and configuration-properties.

Looks like some tests are failing

The new tests were passing, however the old tests were failing. By enabling more logs, it seems OPA v1 + nginx have some problems and OPAClient does not return any response (exception: java.io.IOException: HTTP/1.1 header parser received no bytes). In the 3rd commit, I reverted OPA docker image to the 0.70.0 version and all tests were passed.