Add preference to ignore files in workspace functions

[JonasHelming]

fixed #14448

What it does

adds two settings to specify fles an directories to be ignored by the workspace functions:

• gitignore : Will respect the gitignore file
• User defined list of files or folders

How to test

Ignore files in both settings. Ask the workspace agent "is the a file/folder XYZ in the workspace". Specifically change the .gitignore at runtime to test file watching.

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

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[planger]

Very nice, thank you! The "User Excludes" seem to work very well.

However, in my tests the Git Ignore exclusion doesn't seem to work for the getWorskpaceFileList function:

A few minors:

• The title "Worskpace-function" stands out a bit, because it is the only pref title that uses a "-". In general, I think the labels are not very nice if they are camel-cased. I created a separate ticket on that (Improve AI settings labels #14452)
• I think we should name the preference about user excludes more from the perspective of the user, e.g. "Excluded File Patterns" is better?

[JonasHelming]

@planger I tried to adress all comments.
However, about the described Bug that .gitignore is not respected, I failed to reproduce this. Can you point me to the repo where you tried this?

[planger]

Thanks for the revision! Looks much cleaner now imho!

Please see two more suggestions inline, also regarding the bug I observed. Eitherway, I'm fine with the current state, even though I think my suggestions make sense.

Edit: One more nit... I'd find it better to make the private methods protected, this way, adopters can overwrite them.