validate: launcher: Add support to skip already passed tests

Submitted by Vineeth

Link to original bug (#754052)

Description

If the test has already passed, then it would be good to skip the test and continue with only failed tests. Since the test status will be saved in the log file, by reading the log file, skipping the test case if it already passed. Added a new argument --skip-passed for this scenario...

This might be better to run by default. In that case we can add an argument --force to give an option to force all test cases to be run irrespective of the result.