Option to close path on no demand like runOnDemand in v1.2.0 and earlier

[mrlt8]

Describe the feature

Option to ClosePathOnNoDemand or CloseOnNoDemand. Potentially with a configurable timer CloseOnNoDemandAfter.

In v1.2.0 and earlier, MTX would close a path if runOnDemand was set and there weren't any clients reading, regardless of whether the runOnDemand command started the stream or not. However, this functionality was changed in v1.2.1 and runOnUnDemand will not trigger or close the path if publishing to a path before any clients are reading essentially keeping the path alive until a client starts and stops reading.