Log test case ended events, including issue counts, when running in verbose mode

[stmontgomery]

Description

When running in verbose mode, we should output a message when each test case of a parameterized test function ends, including a count of the number of issues which were recorded for that test case.

This is a follow-on to #943: part of the enhancement described there—logging the number of test cases for each parameterized test function—was implemented in #972. But the other part remains, and is tracked by this issue.

Additional information

No response

[stmontgomery]

This is blocked by #1000: once that's in place, it should make this much easier to implement.

[grynspan]

I could swear we did this already!

[grynspan]

Tracked internally as rdar://146863942.