Make a runtime environment for DNS for Kyoto

[rustaceanrob]

The lookup_host function requires a tokio runtime to execute, but since it is outside of the Node, this function panics when called. Add a runtime, which is essentially an OS thread in this context, to complete the call.

Notes to the reviewers

In the future I could potentially find a more elegant way to do this, but this call should be relatively short and only consume a single thread.

Changelog notice

• Fix lookup_host on CbfClient

Checklists

All Submissions:

• I've signed all my commits
• I followed the contribution guidelines
• I ran cargo fmt and cargo clippy before committing

New Features:

• I've added tests for the new feature
• I've added docs for the new feature

Bugfixes:

• This pull request breaks the existing API
• I've added tests to reproduce the issue which are now passing
• I'm linking the issue being fixed by this PR

[rustaceanrob]

Tested locally with:

let peers = await client.lookupHost(hostname: "seed.bitcoin.sprovoost.nl")

In the LiveKyotoTests.swift and was able to successfully get a DNS response

[reez]

ACK 6f2e566