Add a secret config type to store secrets in the OS provided secret store

[anjannath]

It'll be useful to have a way to store a password/pull-secret in the OS key store directly using the crc config commands.

The end result would be:

• e.g crc config set smb-share-password crcpass (its stored in the OS secret store and 'crcpass' is not written to ~/.crc/crc.json)
• crc config view should mask the value of smb-share-password in its output

[anjannath]

The cli for crc config <cmd> would also need to be modified.. by adding a --show-secrets (or similarly named) flag

• crc config set will remain the same for setting both a normal and secret setting, whereas
• crc config get and crc config view will have a new --secret flag to fetch values from the secret config store

by default --secret boolean flag will be false, i.e get and view will not display the values of the secrets