Structration of code

### What feature do you want to see added?

It's not a feature. But I realized that there are more than 46 classes in the java.io.jenkins.plugins package.
It's getting harder and harder to find the classes.
I was thinking of creating a "trait" folder to put the 16 existing trait classes.
I don't know if this has a big impact on compatibility with older versions?
I don't think other plugins use this one in imports.

### Upstream changes

_No response_

### Are you interested in contributing this feature?

Yes, I can do it. But I don't want too if the community is not OK

If you have any other ideas for structuring, please add it here