Add sigstore bundle support for creation artifact's evidences

[mnsboev]

• 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.
• I used gofmt for formatting the code before submitting the pull request.
• PR description is clear and concise, and it includes the proposed solution/fix.

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Description

Added a new flag --sigstore-bundle to the evidence create command.
Updated the help-output file to include the new flag.
Made predicate and predicate-type optional, as they are not needed when using the --sigstore-bundle flag (since the sigstore bundle contains this content).
Enabled automatic resolution of the subject (subject-repo-path) if it is present in the DSSE envelope in the correct format.

Examples of Usage:

./jf evd create --sigstore-bundle bundle.json
./jf evd create --sigstore-bundle bundle.json --subject-repo-path cli-sigstore-test/commons-1.0.0.txt

Validations:

Possible verification errors to watch for include:

• The parameter --subject-sha256 cannot be used with --sigstore-bundle. When using --sigstore-bundle, the subject hash is extracted from the bundle itself.
• The following parameters cannot be used with --sigstore-bundle: --key, --key-alias, --predicate, --predicate-type. These values are extracted from the bundle itself.
• The --sigstore-bundle is currently not supported for release bundle evidence. This feature may be supported in future releases.

[dortam888]

Approved with small comments