refactor: structure of an hexagonal architecture

Created a kernel crate to store models and future action implementations.
Will be useful to create admin cli.

tests/manual/oauth2c.sh

@@ -0,0 +1,10 @@
+#!/usr/bin/bash
+
+oauth2c http://localhost:8085 \
+  --client-id "a1785786-8be1-443c-9a6f-35feed703609" \
+  --client-secret "49c6c16a-0a8a-4981-a60d-5cb96582cc1a" \
+  --response-types code \
+  --response-mode query \
+  --grant-type authorization_code \
+  --auth-method client_secret_basic \
+  --scopes "user_read_basic"