[Metrics] Log the Selected Type

This logs the selected credential type, by focusing on the response.
This will lose metadata on half-way clicks/mid clicks/etc... - those
might be explorable via the list of tapped entries. In the future,
depending on product need, adding the rest of the string classtypes can
be explored.

Bug: 364444783
Test: Stats_d, eventually chained, build
Flag: android.credentials.flags.fix_metric_duplication_emits
Change-Id: I274692b2d3fe016142ea81c9fe34cbf31aab5566