Add Plug support

[FloorLamp]

Plug is not supported since our custom API authentication uses the identity to sign a message, which Plug does not support yet.

When Plug adds arbitrary signatures, it should added as an authentication method.

[tarek-eg]

Should we also add stoic support? does it have the same issue as plug?

[FloorLamp]

We should, but it might be challenging for them to add arbitrary signatures due to having multiple key management solutions.