Unify API returns to sql composite types, add pattern tests for REST API

Requires haf!634 (merged)

Related with balance_tracker!171 (merged)

• Unifies API responses - adds exception handling instead of null values in composite types
• every api returns sql type instead of json
• fix for /global-state values were shortened by json
• adds patten tests for REST API

tests/tavern/common.yaml

+---
+  name: Common test values
+  description: Common values for tests
+
+  variables:
+    service:
+      proto: http
+      server: "{tavern.env_vars.HAFAH_ADDRESS}"
+      port: "{tavern.env_vars.HAFAH_PORT}"