Add New UiEvents for media dashboard

Adds two UiEvents when media session is added, the first one is logged when the carousel contains only one media player. The second event when the carousel has multiples, it is logged only once.

Bug: 241485754
Test: Tried log.e() and checked that it is working as explained in the
description.

Change-Id: I8380bfd14cde5c38b2940023e7ddce01fe3128ad