For DASH, handle multiple type of audio & text tracks, using dashjs

[Nfrederiksen]

To solve the issue described below, we need to implement a new child class of BaseTech.ts which is powered by the Dashjs library and have it so that the web player will use this new class for playing .mpd streams.

Issue Description
Even if multiple audio tracks, or subtitle tracks, applies to the same language - these should be differentiated in the selection lists by either label or to apply the number of channels (being an audio track) or any other available data onto the naming. To be obvious for the user.