Implement DHT test CLI tool

[gavin-norman-sociomantic]

The current test is suited to being run automatically via make test. It is also sometimes useful to be able to manually run a series of known tests on a DHT node, and to leave the tests running for some period, as per the old dhttest in swarmtools. It shouldn't be difficult to add a small CLI tool to do this.

[gavin-norman-sociomantic]

Mihails mentioned that there may be some complication with the turtle test runner that might make this too tricky to bother implementing, but that was more than 2 years ago, so things may have changed.

[nemanja-boric-sociomantic]

Perhaps we should move neotest into dhtproto.

[gavin-norman-sociomantic]

Well, this issue is about running the existing tests on an arbitrary node. neotest is just a temporary thing, I'd say, while we don't have a proper neo-supporting CLI tool.