Add markdown report

[alenon]

• All tests passed. If this feature is not already covered by the tests, I added new tests.
• All static analysis checks passed.
• Appropriate label is added to auto generate release notes.
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• PR description is clear and concise, and it includes the proposed solution/fix.

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Evidence Verification Report Formats

This pull request introduces a new feature that allows users to choose the output format for the jfrog rt evidence verify command.

The following formats are now supported:

• plaintext (default)
• json
• markdown

This is implemented by refactoring the printing logic to use a ReportPrinter interface, with concrete implementations for each format. This makes it easy to add new report formats in the future.