Add tests for history_request in message spec

I was going through the tests to understand how the do_history call works and found that there is no message spec test for history_request. I added 3 simple tests to check this request. I have run iptest and confirmed there are no issues.
I think this assumes that there was at least one command executed in the current kernel before this test ran. Tests shouldn't assume that they're run in a particular order, or even that any other tests are run: it's possible to run a single test in isolation.

So before making the history request, each of these tests should execute some simple code with store_history=True.