Allow optional path for -dev flag?

[JakeWharton]

I'm wrapping this tool up in a Docker container for easy consumption by the masses (or, at least, by a few people). Inside the container I want people to mount /config as the Chrome directory which is sort of standard. Right now I have no choice but to use -dev to get a stable path, but that goes to /tmp/gphotos-cdp. I can do a symlink, but it would be nice to be able to pass a path similar to -dldir.

Alternatively, if the arg parsing library does not support optional values for arguments, you could consider replacing -dev with -chromedir or -configdir or anything which always takes a path. Development would then change to specifying -chromedir /tmp/gphotos-cdp (or whatever you wanted).

Or you can do nothing and I can still make things work. Just thought I'd propose it.

[JakeWharton]

Any feedback? I'm happy to do this work, I just need the decision to be made.

[mpl]

@JakeWharton just so you get a partial answer: I have no opinion whatsoever on the matter, and I don't have time to form one at the moment. I can only allocate a little time to gphotos-cdp these days, and there are more urgent things I need to fix on it first, sorry.
That said, feel free to open a PR, in the hopes someone else would have the time to look at it.