Don't use cookies.txt, just add the sp_dc token as an environment variable or commandline argument

[jmaximusix]

Since the other cookies seem unneccessary, I found it preferable to just use that and set it either via a commandline argument or as an environment variable. Also added the option to use a .env file for convenience. Also, since I plan on using the Spotify API class outside of the cli, I find it a bit "cleaner" to initialize it with an access token instead of a path to a cookies file of which most are not needed.

Thanks a lot for this repo, I've just forked it to implement some changes / extensions of functionality for myself and will submit changes that I think could be generally useful as pull requests. Feel free to modify or reject this PR if you don't like it.

[glomatico]

That's a nice change, but I'll keep the good and old cookies.txt file for now.