Create E2E tests

[llowinge]

Would be really great if this framework would contain E2E tests which could verify basic yaks workflow as it would create a contract between users and their expectations.

Scenario 1

1. We have yaks-config.yaml containing temporary namespace settings.
2. Create namespace yaks-global-operator
3. yaks install (globally)
4. yaks test (verify temporary namespace was created; no new operator was created in temp namespace and tests passed)

Scenario 2

1. We have yaks-config.yaml containing temporary namespace settings.
2. Create namespace yaks-non-global-operator
3. yaks install (non-globally) - maybe this step is not needed ?
4. yaks test (verify temporary namespace was created and tests passed)

@christophd FYI

[christophd]

Yes, and I think the documentation should outline these workflows and list its individual benefits and possible downsides