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/main.rs

@@ -1,6 +1,10 @@
 #![forbid(unsafe_code)]
 #![cfg_attr(feature = "unstable", feature(ip))]
-#![recursion_limit = "512"]
+// The recursion_limit is mainly triggered by the json!() macro.
+// The more key/value pairs there are the more recursion occurs.
+// We want to keep this as low as possible, but not higher then 128.
+// If you go above 128 it will cause rust-analyzer to fail,
+#![recursion_limit = "87"]
 
 extern crate openssl;
 #[macro_use]