Adding async storage helpers

[JDMathew]

Added helpers for async storage

Closes: #130

[keithluchtel]

Are these needed for anything in particular at this point?

[JDMathew]

Yeah, I'll be using the string values when storing the mode but I thought I may as well add all the helper functions at once

[keithluchtel]

I thought we were going to put the preference in Zustand?

[JDMathew]

My vision was that Zustand would persist Aysnc storage functions that get the mode. Zustand would also call Async storage functions that set the mode. These mode storage functions call generic asyn helper functions to set and get values. This PR is adding those generic async functions

[keithluchtel]

I was thinking we'd use the built-it persistence middleware to handle storing the store to AsyncStorage and wouldn't need these helpers: https://github.com/pmndrs/zustand/blob/main/docs/persisting-store-data.md

[JDMathew]

I was thinking we'd use the built-it persistence middleware to handle storing the store to AsyncStorage and wouldn't need these helpers: https://github.com/pmndrs/zustand/blob/main/docs/persisting-store-data.md

Right, I was seeing persist as just hydrating now handling the storage with getters and setters. Will use this approach.

Is it worth us having these async helper functions in the codebase anyway?

[keithluchtel]

Let's keep this PR around and can merge it through when we have a valid use-case for them.