Signature validation - Fallback to use storage API

[orto17]

• All tests passed. If this feature is not already covered by the tests, I added new tests.
• This pull request is on the dev branch.
• I used gofmt for formatting the code before submitting the pull request.
• Update documentation about new features / new supported technologies

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[eranturgeman]

Review: Signature Validation — Storage API Fallback

Verdict: REQUEST_CHANGES

The verifyArtifact.sh fix is correct and solves the immediate release-pipeline failure. The refactoring into load_remote_checksums_jf/curl → compare_local_to_remote is clean.

One functional bug exists in getFrogbot.sh's storage_request(): the auth guard uses REMOTE_PATH as a proxy for "private instance" instead of checking for credentials directly. This diverges from the correct pattern already used in verifyArtifact_storage_request_curl() in the same PR, and will silently omit auth for users who set FROGBOT_BASE_URL without REMOTE_PATH.

CI status: Azure Integration Tests (all 3 platforms) and Bitbucket Server Integration Tests are failing. Please confirm whether these are pre-existing infrastructure failures or regressions introduced by this PR.