kunit: tool: delete kunit_parser.TestResult type

The `log` field is unused, and the `status` field is accessible via
`test.status`.

So it's simpler to just return the main `Test` object directly.

And since we're no longer returning a namedtuple, which has no type
annotations, this hopefully means typecheckers are better equipped to
find any errors.

Signed-off-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>