Macro recursion decrease and other optimizations

- Decreased `recursion_limit` from 512 to 87
  Mainly done by optimizing the config macro's.
  This fixes an issue with the rust-analyzer which doesn't go beyond 128
- Removed Regex for masking sensitive values and replaced it with a map()
  This is much faster then using a Regex.
- Refactored the get_support_json macro's
- All items above also lowered the binary size and possibly compile-time
- Removed `_conn: DbConn` from several functions, these caused unnecessary database connections for functions who didn't used that at all
- Decreased json response for `/plans`
- Updated libraries and where needed some code changes
  This also fixes some rare issues with SMTP https://github.com/lettre/lettre/issues/678
- Using Rust 2021 instead of 2018
- Updated rust nightly

src/db/models/two_factor.rs

@@ -159,7 +159,6 @@ impl TwoFactor {
 
         use crate::api::core::two_factor::u2f::U2FRegistration;
         use crate::api::core::two_factor::webauthn::{get_webauthn_registrations, WebauthnRegistration};
-        use std::convert::TryInto;
         use webauthn_rs::proto::*;
 
         for mut u2f in u2f_factors {