[SNAP] Implement Screen Compare

[Blackjacx]

Expectation

Implement screen comparison functionality as sub command of Snap so that this can be called like

mint run Blackjacx/Assist@"develop" snap compare \
	--workspace "<project_name>.xcworkspace" \
	--scheme "DBFFM" \
	--branch "my-feature-branch" \ # <-- THIS IS NEW (defaults to the current branch)
	--comparison-branch "develop" \ # <-- THIS IS NEW (defauts to develop)
	--test-plan-name "Screenshots" \
	--test-plan-configs "en_GB" \
	--destination-dir $(mktemp -d) \
	--zip-file-name "Screenshots-$(date +%F_%H-%M-%S).zip" \
	--appearances "light" \
	--devices "iPhone 15 Pro" \
	--runtime "iOS 17.5" --verbose

Issues

• Resolve https://github.com/dbdrive/ios-tools/issues/34