Enhance rpm validation workflow with distribution signature check

[zelinh]

Description

Enhance rpm validation workflow with distribution signature check.
The standard output when we run rpm -K -v on s signed RPM distribution file will be like below:

- rpm -K -v /tmp/workspace/yum-download/opensearch-2.0.1-linux-arm64.rpm
/tmp/workspace/yum-download/opensearch-2.0.1-linux-arm64.rpm:
    Header V4 RSA/SHA512 Signature, key ID 9310d3fc: OK
    Header SHA256 digest: OK
    Header SHA1 digest: OK
    Payload SHA256 digest: OK
    V4 RSA/SHA512 Signature, key ID 9310d3fc: OK
    MD5 digest: OK

While on unsigned distribution files, there would be either saying NOKEY or lack of certain type of signature digest.
This enhancement check will check two aspects:

1. Check if all signatures are OK.
2. Check all six above signature digest present.

Issues Resolved

#2197

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