add Vuex store

[eswat2]

create a simple Vuex store to replace the embedded store

1. store with simple mutations
2. actions issue commits to mutate store
3. remove event mechanism to push changes
4. containers access data via the store
5. leave event mechanism to invoke actions (phase 1)

[eswat2]

Phase 2:

1. move actions into store
2. invoke actions with store.dispatch

[eswat2]

Need this for Vue3 and Vuex next