Support action labels as input to execution:get-step-log and execution:get-quality-gate-result

As described in #226, it would be helpful if the label (i.e. "Build Image") could be provided as the action option to these commands.

This is likely dependent upon https://github.com/oclif/parser/issues/162. It is doable without that change in @oclif/parser, but option validation would have to be reimplemented so it would be best if @oclif/parser supported that directly.

Start by reviewing the execution:get-step-log and execution:get-quality-gate-result command entry points, then read the dependency described in #226 and the linked @oclif/parser issue. Done means both commands accept action labels such as "Build Image" as the action option while preserving option validation.

Written by the indexing model from the issue text.