New feature to report unknown rules / warnings

[jenspopp]

This is a fix for #2586

I tested it with gcc, cppcheck and clangtidy.

Open points:

1. Default unknown rule is right now only for the tested frameworks in the xml definitions
2. We could use protobuf instead of json (but at least for my local use case it was so fast, that I didn't see a reason to invest time here)
3. In the long run we might need to replace all "-" with "_" in the rule ids.... (due to sonar community changes)
4. I'm not sure, I covered all possible exceptions (e.g. with login/authentication); but they should occur already before the cxx plugin
5. Right now only login with token is supported

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This change is 

[guwirth]

Hi @jenspopp,

thanks for providing this I will have a look to it.

Regards,

[guwirth]

@jenspopp thx for fixing the tests

[jenspopp]

@jenspopp thx for fixing the tests

Hi, please note that some tests will fail with Java 17 due to some Exception changes in 17....

[guwirth]

Risk too high to add this to V2.1 version,will be merged into V2.2 version.