Combine ssh_login and ssh_login_pubkey modules

[dwelch-r7]

Resolves #14902

Combines the ssh_login and ssh_login_pubkey modules for an improved user experience

There will be an accompanying Pro PR so I will draft this until we're sure Pro works with these changes

my setup for testing can be found here #20546

Verification Steps

• Run the ssh_login module and gain a session with username/password
• Run the module again and gain a session with a non-password protected private key (via KEY_PATH and PRIVATE_KEY)
• Run the module again and gain a session with a password protected private key (via KEY_PATH and PRIVATE_KEY)

[dwelch-r7]

realising this section is very similar between the two login methods bar the slight different in printing, I can probably DRY this up too