Move `Meditor`/`VJsfWrapper` shared state into a `state.ts` file

Since `transaction-tracker` and `editor-interface` never change (they are singleton instances), we could factor them out into a shared state. Vuex wouldn't be totally necessary, as the state does just apply to the meditor, but we could move `Meditor.vue` and `VjsfWrapper.vue` into their own `Meditor` folder, and place any shared state in a `state.ts` file. This would allow us to take advantage of composition API without needing to clutter the store. What do you think?

_Originally posted by @AlmightyYakob in https://github.com/dandi/dandi-archive/pull/862#discussion_r802010555_