Added heartbeat timeout option to Run

[kzscisoft]

Adds the timeout argument to Run.init to specify the timeout period for the run where setting it to None disables the timeout.

Closes #494

[james-panayis]

Would be nice if there was a test that tried the case where the timeout is set to None (and ideally then waited over 180 seconds to confirm that the run doesn't end up in the lost state).

[kzscisoft]

@james-panayis The issue with that is it will be a significant extension to CI execution time

[james-panayis]

@kzscisoft if you did the wait then sure, that'd increase the CI time. But just confirming that a run can actually be created with timeout None would not take especially long. I mostly would just like a test to confirm that the server will correctly interpret the request as an instruction to create a run.

[kzscisoft]

@james-panayis good point, the validation was not allowing None! So this test picked that up. Added it in now 🙂