Implement reader for Syslog RFC5424

[knapperzbusch]

This PR adds a Syslog parser and reader. With this, it is possible to import Syslog messages in the format defined in RFC5424. If a message can't be parsed, the message will be handled as single string.

[dominiklohmann]

Thanks for your contribution! 🚀

Can you do a first pass of rebasing? Ideally, this would be just five commits:

1. Add Syslog parser (RFC5424)
2. Add unit tests for Syslog parser
3. Add reader for Syslog
4. Hook reader into command line
5. Add integration tests for real-world Syslog data

Additionally, please do a pass over your code after reading our contributing guide.

Other than that, this is looking quite good already. I'll do a second pass tomorrow that's more code-specific.

[dominiklohmann]

I've done a second pass.

[dominiklohmann]

I have done another pass.

[dominiklohmann]

@knapperzbusch should this still be in draft mode?

[knapperzbusch]

I will do rebase with master today night or tomorrow morning, to resolve the conflicts.

[dominiklohmann]

Sounds good. Will do one last review pass then (likely next week), so we can get this merged.

[dominiklohmann]

I took the freedom to rebase this once more and rewrite some comments—no more code changes were necessary.

Thanks for your contribution, @knapperzbusch! We'll merge once CI has run through successfully.

[dominiklohmann]

Great work! 🚀