By default, print the total time taken to execute a test suite

[matklad]

At the moment, the test output looks like this:

running 514 tests
.................................................................................................... 100/514
.................................................................................................... 200/514
.................................................................................................... 300/514
.................................................................................................... 400/514
.................................................................................................... 500/514
..............
test result: ok. 514 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

It would be very helpful if the last line said

test result: ok. 514 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; 9.2s

I think we should print this by default, without any kind of flag.

This is related, but not equal to --report-time options: #64663

cc @jakoschiko

[jakoschiko]

I'm interested in implementing this.