Added option exclude symbols

[Sidelobe]

Hi Xavier

I've been using coverxygen for some years in a "documentation coverage gate" in build pipelines. Since I did not want this gate to annoy devs and force them to write docu for self-evident functions -- commenting "this is the default constructor" does not add any value.

Therefore, I've extended coverxygen to support a new --excludesymbols option.
As another example, I'm using this regex to exclude any function that starts with get, set, is, has, can: .*[:|_][get|set|is|has|can]([A-Za-z0-9_-]+)\(.*\).*

I've added relatively thorough tests that use your class.xml test data and have updated the README with the output from --help.

Let me know if I missed anything,
Lorenz

[Sidelobe]

Awesome 🥳
thanks for fixing the CI