Print messages once, as to not flood console

[timtebeek]

What's changed?

• Only print notes once
• Assert there's no messages in tests
• Fix and enable disabled tests

What's your motivation?

As per #5 I was looking to add this to error-prone-support, but noticed we flood the console with repeated messages there, mostly pending #21.

Any additional context

• 5

• 21

• https://github.com/openrewrite/rewrite-migrate-java/commit/4bfadd20f38ec86ccbe80aaa77789c23d3ec3cd7

[timtebeek]

I think we can also close #5 ; we sufficiently skip unknown elements, which was the goal there.