Add equivalent of "hover" for touch displays

**What is the current behaviour and why should it be changed?**

On desktop builds, hovering the mouse over the channel user displays their profile details in a tool tip:

As no "hover" action is available for touch displays (e.g. Android), this feature is unavailable.

**Describe possible approaches**

A single tap or, probably better, long-hold could be used to display tool tips in general. (Long-hold would avoid misinterpretation of single tap on a checkbox or menu, etc.)

I'm guessing touch screens also are missing right-click "What's this?" support. Possibly that could be implemented as above, with "Show musician profile" as an extra option where applicable.

Other trigger actions could be double tap or two-finger tap. Long-hold is prefered, I think.

**Has this feature been discussed and generally agreed?**

Only with my partner, who raised it.

Inizia individuando il tooltip hover desktop per gli utenti del canale e il comportamento di «What's this?» con il clic destro, quindi esamina come viene gestito l’input touch. L’issue richiede un gesto concordato e dovrebbe essere considerata completata quando un tocco mostra il tooltip pertinente o il profilo del musicista senza interpretare erroneamente i tap sui controlli.

Scritto dal modello di indicizzazione a partire dal testo della issue.