[FEATURE]Add hex encoding support for password and UUID generators

[ferrohd]

Is your feature request related to a problem? Please describe.
I'm always frustrated when I need to generate secrets that should be in hexadecimal format for certain applications and configuration systems. Currently, the secret generator supports base32, base64 (and variants), but doesn't support hex encoding, which is a very common format for representing binary data in configuration files, API keys, and cryptographic contexts.

Describe the solution you'd like
I would like the ability to specify encoding=hex, similar to how other encodings work. This should allow me to use:

• %generate:password:encoding=hex - to generate a password and encode it as hexadecimal
• %generate:uuid:encoding=hex - to generate a UUID and encode it as hexadecimal

Describe alternatives you've considered

• Custom symbols in password generation: Try to use only hex characters (0-9, a-f) as symbols, but this doesn't provide true hex encoding of the underlying binary data.

Additional context

• Hex encoding is widely used in DevOps and configuration contexts
• Many applications expect secrets/tokens in hexadecimal format
• This would maintain consistency with the existing encoding options

I'm willing to work on implementing this feature if the maintainers approve this enhancement. I've already opened a PR, if you don't want this change feel free to close it.