arg --fix-db won't panic anymore

[restalex]

...due to missing directory or unexpected files.

• Idiot-proofing the use of --clear-cache before --fix-db (cause I am one)
• --fix-db does not panic anymore if a file has no extensions according to the extension() method. Happened to me with the .directory files that uses the dolphin file explorer.
• added a description for --clear-cache if an invalid argument is given. (adding a -h argument could be nice too?)

However --fix-db does not lauch the TUI after being done, nor it removes any of the faulty json or mp4 files, which option seems best?

I quite like this project, as it has all the base features I want for a YTmusic player. So I eventually decided to contribute even if I'm a newcomer to rust.
I will try to work on #93 and/or #88 on my spare time, because I need that the most.

[ccgauche]

Thanks a lot for the contribution. I left you some areas for improvements. What would be the use of the -h argument ?

[restalex]

Second commit is the end of the --fix-db:

• a lot of match cases to properly dispose of the jsons
• fixed the clean task, that was not deleting orphan mp4s. The ends_with() example recommends to use extension() instead.

Third commit is an example of what i mean by an -h argument, just a small explanation of what ytermusic is and can do. And especially the shortcuts that I often forget.

[ccgauche]

In rust, you don't need the comma after the format string if no arguments are given.

Suggested change

	println!("[WARN] No download directory found in Cache",);
	println!("[WARN] The download folder in the cache wasn't found `{cache_folder}`");

[ccgauche]

Use cargo fmt to format the code

[ccgauche]

Don't use an else prefer using a return to end the function there.

[ccgauche]

Could be a good idea indeed!