bug: fs.cat hanging

[SgtPooki]

discussed 2023-09-28

We are currently optimistically leaving CID in WANTLIST because we assume it will resolve, but it's not. The expectation is that a user would pass in an AbortSignal.

The promise that bitswap returns doesn't resolve: no FINAL_PEER. If we query all peers we know about.... then we should be done and exit, regardless of AbortSignal.

### Tasks
- [ ] the query SHOULD end but doesn't (provide repro) 
- [ ] If we fail to find providers we should fail the whole thing

[SgtPooki]

There was a comment in https://pl-strflt.notion.site/Discussion-what-makes-it-hard-to-contribute-to-the-stack-7db6860f155a4dacaabfbda3ce31e94d?pvs=4 regarding doing a timeout per block. @achingbrain can you provide more context around that?

[SgtPooki]

CID sticks around in the wantlist, even if we are unable to find any providers. We should error instead, and allow users to override that behavior.

• If user doesn't pass in abort signal, and we don't find providers, we should error immediately.
• if you unwant a CID, you can force any promises waiting for the resolution of that content to fail.

"i dont think any user prefers fs.cat hanging" - @achingbrain