Feature: Set LocalStorage and Context When a Customer Logs In

[larkinds]

Overview
When a customer logs in, we want to persist their login across all pages of the application - even if they navigate away from the website briefly. To do so, provide a context for all pages of the webpage and set localStorage.

This issue depends on #43 being complete.

Actions

• Set up context for the application, at the top level (main.tsx)
• Update useContext to reflect the currently signed in user’s username
• Set localStorage with logged in user’s username
• Set expiration datetime for localStorage
  - [ ] For products
  - [ ] For customer login status
• If there is already state persisted within the application when a user logs in (in either reducer) make sure that state does not change
• You’ve checked that you’ve followed the [Rules of Hook](https://legacy.reactjs.org/docs/hooks-rules.html
• Handoff to the team implementing the header

Resources
React's Guide to Context
useContext API