FR: Add added(), deleted(), clean(), ignored(), conflicted() and resolved() fileset functions

[AngelEzquerra]

Is your feature request related to a problem? Please describe.
When creating a colocated jujutsu repo on an existing repo that has some untracked but not gitignored files, they are added to the working directory revision automatically. In order to untrack them all in one single command, it'd be great to have a way to refer to all of them using a fileset such as "added()". This exists in mercurial and it is quite handy. In addition to that it would make sense some of the other missing fileset functions, such as clean(), ignored(), etc. It would also be nice to have filesets to find conflicted files.

Describe the solution you'd like
Adding those missing functions (e.g. added() would return the list of files added on a revision, etc)

Describe alternatives you've considered
I don't think there are any.