Feature/stats endpoint (#631)

* Idea for stats endpoint

* Introduced /stats endpoint replacing sending data to metrics server

* Removed metrics client

* Removed old metrics file

* cargo fmt

mixnode/src/node/http/mod.rs

@@ -1,4 +1,5 @@
 pub(crate) mod description;
+pub(crate) mod stats;
 pub(crate) mod verloc;
 
 use rocket::Request;