util: Implement key name support for `Keychain` and `KeychainServer`

[xdustinface]

This PR implements key name support for the Keychain and KeychainServer classes.

Changes to the daemon websocket interface:

• Adds the new command set_name to set a name for fingerprint
• Adds the new command delete name to delete the name for fingerprint
• Adds the name parameter to the add_private_key method to assign a name when adding keys

Based on:

• #12830
• #12843