Feature - Add a timeout to Emily requests

1. Description

The sbtc signer has timeouts on some requests, but not others. Requests to the signer's stacks node have a timeout, while requests to Emily or their Bitcoin node do not. We should always have a timeout on our requests so that we do not stall one of the signer's long lived processes with a request that takes an unreasonable amount of time.

2. Technical Details

The Emily and Bitcoin clients have interfaces where we can set a timeout on various aspects of a request. We should set them.

• Requests to bitcoin core and Emily have a maximum amount of time that they could take.

3. Related Issues and Pull Requests (optional)