Use masked values for secret values

[orhun]

We should use e.g. SecretString from secrecy (instead of std::string::String) for handling sensitive values such as:

rustypaste/src/config.rs

Line 54 in 8954ce4

pub auth_token: Option<String>,

[tessus]

Hmm, this is probably not a good first issue. One problem is that that it is not pssible to have a HasHset<SecretString>.
I searched a bit, but couldn't find a solution, but I guess my Rust knowledge is limited...

[orhun]

Hmm I guess that's because SecretString does not implement Hash and Eq... It might be worth reporting it to upstream to get it fixed.

[tessus]

@orhun I think you are more qualified to continue the discussion at iqlusioninc/crates#1299