Improve --progress and --report output

[cgay]

For example, the failures report now looks like this:

$ _build/bin/testworks-test-suite-app --progress none
FAILED: testworks-test-suite-app
  FAILED: test-assert-equal-output
    FAILED: b
      1 (from expression "1") is not an instance of {class <string>}.
    FAILED: f
      no condition signaled
    CRASHED: g
      Error evaluating assertion expression: foo
    FAILED: list, same size, different elements
      want: #("a", "b", "c", "d")
      got:  #("a", "b", "x", "d")
      detail: element 2 is the first mismatch
      ...
Ran 1289 assertions
Ran 54 tests and 2 benchmarks: 1 failed and 4 expected failures
FAILED in 0.312805 seconds