Support for working offline by saving heartbeats locally

[alanhamlett]

Editor plugins support offline coding, and this extension should too. It could store heartbeats in chrome.storage.local with a capacity of 5MB. This would be local to the user's computer and not synced, since the chrome.storage.sync limit of 100KB is too low.

[ramajd]

it will be very good having this feature supported. since wakatime connection issues could happen occasionally.

[jvelezpo]

V3 already hasIndexedDB integrated which supports storage capacity over 50MB which should be fine IMO for the extension/addon Here is where it gets created.

This means when a user gets disconnected from the internet we store heartbeat inIndexedDB, once we detect the user is back online we send the heartbeats to Wakatime API