android client is unable to log in from within rustdesk client using oidc

[akarl10]

First of all, Thank you for the great addition of this api server to rustdesk.

I did some tests and noticed that android is not able to login.
The issue is that the uuid that it passes on the api/oidc/auth is not a base64 encoded hex string but instead binary.

let uuid_client = String::from_utf8(uuid_decoded).unwrap()

fails in this case (with a unhandled error, the webserver returns a 500 error)

I think the uuid can be used as a blob (the fact that it's base64 encoded is probably only to be able to insert into a json)