Add --threads (-t) option to downloading commands

[valentinegb]

This PR adds a threads field to DownloadBuilder and Downloader and adds a --threads (or -t for short) option to the download and archive commands. This overrides the cores that Downloader utilizes for downloading. This is useful in situations such as my own where having one program utilize all cores for downloading renders the rest of the device practically unusable. I understand that the name --threads might not be entirely accurate as to what it does since I think the number of threads tokio uses is the same to some extent even with this new option, so I'm open to suggestions for a more accurate name.

[bytedream]

This could be extended to be a command to specify the thread count instead of only single threaded

[valentinegb]

This could be extended to be a command to specify the thread count instead of only single threaded

True, that'd be pretty easy, but do you mean a command or an option? I feel like an option would make more sense.

[bytedream]

Yes an option/flag. So instead of --single-threaded, --threads which takes the thread number as argument

[valentinegb]

Yes an option/flag. So instead of --single-threaded, --threads which takes the thread number as argument

Okay, sure, I'll do that later today 👍

[valentinegb]

Yes an option/flag. So instead of --single-threaded, --threads which takes the thread number as argument

Done :)

[bytedream]

Okay nice. Just one more thing which came me in mind. Instead of the flag being Option<usize>, it could directly be usize with the default value of num_cpus::get. With this the user directly knows how many threads are used by default when doing crunchy-cli <command> --help

[valentinegb]

Okay nice. Just one more thing which came me in mind. Instead of the flag being Option<usize>, it could directly be usize with the default value of num_cpus::get. With this the user directly knows how many threads are used by default when doing crunchy-cli <command> --help

You got it 👍

[bytedream]

Looks good :) 👍