[FEATURE REQUEST] Support asymmetric signature operations

[lkubb]

Is your feature request related to a problem? Please describe.
Salt has supported cryptographic operations with GPG for a long time. While it is the most widely used algorithm, there are other ones that are in use. An example are plain asymmetric signatures, without the reliance on GPG-specific constructs such as keyrings.

Describe the solution you'd like
Add an asymmetric execution module that allows to sign and verify data using plain private/public keys, such as in use for X.509 certificates, without any external dependencies.

Describe alternatives you've considered

• Add the module as a custom one
• Create a Salt extension

Additional context
I know the current general trend is to make Salt core lean, but wanted to offer this nonetheless since it is not much code and broadly useful.
This is related to #66527.