kunit: tool: make --raw_output=kunit (aka --raw_output) preserve leading spaces

kunit: tool: make --raw_output=kunit (aka --raw_output) preserve leading spaces

With
$ kunit.py run --raw_output=all ...
you get the raw output from the kernel, e.g. something like
> TAP version 14
> 1..26
>     # Subtest: time_test_cases
>     1..1
>     ok 1 - time64_to_tm_test_date_range
> ok 1 - time_test_cases

But --raw_output=kunit or equivalently --raw_output, you get
> TAP version 14
> 1..26
> # Subtest: time_test_cases
> 1..1
> ok 1 - time64_to_tm_test_date_range
> ok 1 - time_test_cases

It looks less readable in my opinion, and it also isn't "raw output."

This is due to sharing code with kunit_parser.py, which wants to strip
leading whitespace since it uses anchored regexes.
We could update the kunit_parser.py code to tolerate leaading spaces,
but this patch takes the easier way out and adds a bool flag.

Signed-off-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>