Abstracted CommandHelper module

[#81219724]

Signed-off-by: Michael Maximilien <maximilien@acm.org>
Fixed git fetching without repo in ci:promote

[#81219724]

Signed-off-by: Michael Maximilien <maximilien@acm.org>
Fixed build.promoted?

[#81219724]

Signed-off-by: Michael Maximilien <maximilien@acm.org>
Added logging to ReleaseChangePromoter

[#81219724]

Signed-off-by: Michael Maximilien <maximilien@acm.org>
Fixed stemcell artifact paths

- Numbered version in pipeline gets copied to 'latest'
- Removed duplicate '.tgz' in the file name

[#81219724]

Signed-off-by: Michael Maximilien <maximilien@acm.org>