extend testing library

[Diaphteiros]

What this PR does / why we need it:
Adds two functionalities to the testing library:

• The (Complex)Environment can now be instructed to inject UIDs into k8s objects, which the fake client doesn't do by default.
• Further methods have been added to match the error returned by a failed reconciliation, which was not possible with the ShouldNotReconcile function (and its relatives) before.

Which issue(s) this PR fixes:
Required for openmcp-project/openmcp-operator#67
Required for openmcp-project/mcp-operator#103

Special notes for your reviewer:
Refactored out of #66

Release note:

The testing library's `ComplexEnvironment` and `Environment` types can now be configured to add UIDs to created resources (the fake client doesn't do this). Use the `WithUIDs` method in the builder and additionally use `InjectUIDOnObjectCreation` if you overwrite the fake client's interceptor funcs to enable this functionality.

Next to the `ShouldNotReconcile`/`ShouldEventuallyNotReconcile` methods from the testing library's `Environment`/`ComplexEnvironment` types, there are now `ShouldNotReconcileWithError` and `ShouldEventuallyNotReconcileWithError` which allow to verify properties of the error returned by the reconciliation in addition to ensuring that one occurred.