Harden aw-client

[ErikBjare]

aw-client is currently not as resilient against failure as it ought to be.

Problems:

• RequestQueue does not safely write back to disk on failure.
• RequestQueue currently supports arbitrary queued requests, but it's not written with such things in mind (only heartbeats).

I found this library persist-queue which might be a better way to handle this.

Related issues:

• AFK and window watcher suddenly stopped logging #164

[ErikBjare]

See my attempt at switching to persist-queue here: ActivityWatch/aw-client#28

[ErikBjare]

Downgrading priority since we merged the persist-queue PR.

[johan-bjareholt]

All problems specified in the issue are now fixed, why not close this issue?
If we find some other place where aw-client is not resilient enough we could create a new issue for that.

[ErikBjare]

Oh, I guess it is. Closing 😄