Auto merge of #64663 - jakoschiko:report-time, r=alexcrichton
libtest: Add --report-time flag to print test execution time
Implements the flag `--report-time` to print the execution time of each executed (successful or failed) test.
Closes #46610
# Example
`cargo test -- --report-time` produces the following output to stdout:
```
running 6 tests
test tests::ignore ... ignored
test tests::noop ... ok 0.000s
test tests::should_panic ... ok 0.000s
test tests::panic_after_10millis ... FAILED 0.010s
test tests::sleep_100millis ... ok 0.100s
test tests::sleep_10secs ... ok 10.001s
failures:
---- tests::panic_after_10millis stdout ----
thread 'tests::panic_after_10millis' panicked at 'foo', src\lib.rs:31:9