Add folder mode

[PauldeKoning]

Thanks for the script everyone.

Changes

I added a 'folder mode' argument that takes the argument and reads the given directory, then parses the files in it as normal, regardless of file extention.

Why

I had it working on my work macbook (m3), however I was fooling around with it relentlessly on my personal PC (Windows + WSL2). I could not get it working for the life of me with the provided examples or while fooling around with the command.

Does it work?

I tested it on my local windows machine using WSL2 ubuntu 22 with 'moreutils' (for sponge) and 'postgres' installed. Using node v22 I ran the script beneath which resulted in the proper output as I got on my macbook without folder mode.

node cli.js --folder-mode --stops-location-index --require-dependencies -u -- gtfs | sponge | psql -h localhost -p 5432 -b -U postgres

(folder in example script is ./gtfs including all gtfs.txt files)

[derhuerst]

As gtfs-via-postgres is designed currently, the shell takes care of globbing (expanding the glob into a set of paths).

This has some advantages:

• Users can use their shell's familiar glob syntax.
• Shells usually have a more powerful glob syntax (e.g. bash) than what most glob-supporting tools implement.
• It keeps the tool lean, they don't need to bother with the complexity of glob syntaxes, plain files vs. directories vs. others, etc.

However:

• Users need some level of familiarity with the shell to know how to make use of globs.
• Some shells don't have (proper) globbing support](https://stackoverflow.com/a/72468013/1072129), forcing users to implement workarounds.

As-is, I'm inclined to reject this PR because it opens up a "pandoras box" of edge cases and new feature requests:

1. support exlusion patterns
2. support inclusion patterns overriding exclusions
3. support recursing into directories
4. etc.

However, I'd like to know how I can help future users figure out how to use gtfs-via-postgres. Make some docs on how to do the globbing on WSL2 would help?