Switch to proper robust data storage implementation

[jthrilly]

We need to use appropriate storage adaptors for redux-persist because localStorage can be erased at any time by the OS, and has varied limits across platforms: https://cordova.apache.org/docs/en/latest/cordova/storage/storage.html

This will lead to sudden spontaneous data loss.

It is also very slow (serialize/deserialize) and has limits on what it can represent.

Existing adapter options are listed on the redux-persist repo: https://github.com/rt2zz/redux-persist

It looks like an optimal solution would be to find a way to use SQL lite across electron and cordova. This may require writing our own plugin for cordova. Cordova plugin is here: https://github.com/storesafe/cordova-sqlite-storage

Potential plugin already developed here: https://github.com/sumedh22/redux-persist-cordova-sqlite#readme

IndexedDB, localStorage, localForage, and web SQL are all not appropriate, since they are also susceptible to OS deletion on iOS.

This relates to #1066, and will ideally contribute to solving it. For example, we might choose to put each session in its own SQL lite database.

[wwqrd]

I did some investigation on this, and I'm not sure a persist plugin is what we need if the store is getting too large.

What might work well is some custom redux middleware which sideloads the sqlite data as and when it's needed - something like the following perhaps?:

const sessionsStore = store => next => action => {
  switch (action.type) {
    case 'persist/REHYDRATE':
      // inject session from sqlite if an active sessionId
    case 'SET_SESSION':
      // load session from store
    case 'END_SESSION':
      // save session to db
    default:
      return next(action);
  }
};