refactor: introduce SessionCtx to hold non-state-machine state (#321)

* Introduce new SessionCtx to hold state that isn't part of the state machine state

* Move application into SessionCtx

* Add refactor to the list of supported PR tags

Author: davidsteiner

.github/workflows/lint-pr-title.yml

@@ -22,5 +22,6 @@ jobs:
             fix
             feat
             chore
+            refactor
             deps
             docs