add: endpoint /tags

fix: leaks from config (now using static length for config strings)

tests/tavern_tests/3.0.tags.tavern.yaml

@@ -97,3 +97,12 @@ stages:
         number: !int "{returned_number:d}"
         controller_id: "{returned_id}"
         tag: "{returned_tag}"
+
+- name: "[tags] get tags"
+  request:
+    method: GET
+    url: "http://localhost:5000/api/v1/tags/"
+  response:
+    status_code: 200
+    verify_response_with:
+      function: validate_tag:multiple