feature(Execution): Allow ignoring failed stages

[AbdulRahmanAlHamali]

Goes with:
spinnaker/gate#1452
spinnaker/orca#4113

[spinnakerbot]

The following commits need their title changed:

• 85d544a: feat(kubernetes): Raw resources UI MVP

• 22ec587: allow ignore failure

• 0daf017: add the directive

• a2f156f: import allow ignore failure module

• 728aec0: add ignore action

• 124187f: fix reason

• 2ed7cd6: fix display of details

• 53551e5: optional display of exception

Please format your commit title into the form:

<type>(<scope>): <subject>, e.g. fix(kubernetes): address NPE in status check

This allows us to easily generate changelogs & determine semantic version numbers when cutting releases. You can read more about commit conventions here.