feat: allow passing a folder as input

[NTFSvolume]

CDL will read URLs from every .txt file within that folder (non recursive). The name of each file will be used as an input group for the URLs within that file.

--update-last-forum-post will not work when the input is a folder

[jbsparrow]

This seems like a really nice feature but I think that supporting recursive folders might actually be a good idea. I think that it would allow users to organize their input directory much more cleanly.

They could then have a structure like:

input
    - forums
        - onlyfans
            - model
                - coomer
        - fansly
            - model
                - coomer

Or something of the sort. I think that example might be a bit of a stretch, but I could certainly imagine it being useful for sorting by ethnicity or really anything the users might come up with.

[NTFSvolume]

I didn't want it to be recursive to prevent CDL from scanning every .txt file on the drive by user error.

I will remove the folder functionality from --input-file and add an explicit --input-folder instead to support recursiveness