Request for option to print/return only the hash value

[rhash]

Discussed in https://github.com/rhash/RHash/discussions/217

^{Originally posted by JavascriptCockup September 19, 2022} As title, would like an even simpler version of the --simple output format option, where only the actual hash value is returned - no filename or other information.

I think good name for the command line option would be one of: --no-filename, --no-path, --only-hash.

For quick workarround see @greisch answer in #217.