feat:(worker) debug element display buffer in worker mode

[Florent-Bouisset]

This PR aims to add the segment inventory sink representation in the debug element of the RxPayer when it's working in worker mode.

[peaBerberian]

when it's working in worker mode.

Just in case for users that might read that PR, by "worker mode" we mean here the "multithreading" mode which is available when the experimental MULTI_THREAD feature is enabled ("worker" here refers to the HTML WebWorker we instantiate to run logic in another thread).

For now we provide under that mode less information in the debug element that can be displayed when adding the optional DEBUG_ELEMENT feature and calling the createDebugElement RxPlayer method.
It sounds like a rare scenario but it isn't at all, most notably at Canal+, where the "multithreading" mode is relied on on many devices.