Detect offline client

[Blazing-Mike]

Context (Problem, Motivation, Solution)

Link related issues! https://github.com/0xFableOrg/0xFable/issues/35

Describe Your Changes

Checklist

• [x] I have performed a self-review of my code
• [x] I ran make check and fixed resulting issues
• [x] I ran the relevant tests and they all pass
• [ ] I wrote tests for my new features, or added regression tests for the bug I fixed

Testing

I implemented a modal to display when our app is offline. so how did i test this, i tested this by throttling the network in my devtools and also disconneCTING my device from wifi and this modal appears on the index.tsx and play.tsx page. when i toggle back or reconnect, the modal disaappears

Cc: @norswap