Change CLI to use clap

[Vaimer9]

Changes CLI setup from manual to use the clap crate. Makes it easier to maintain and more fool proof.

!! Need further recommendations for "short names" for certain CLI flags, like dir which is currently -r.

[Gers2017]

Hey @Vaimer9 thank you for this pr!

I reviewed your code and here's my feedback:

• Using dir instead of EntryType is more efficient. (I like it)

if config.dir == is_dir && config.is_match(&name) {
    result.push(entry.path());
}

• Flags are missing their descriptions.
• It looks like clap is slowing down the program.
  

Could remove clap and leave the dir field?