Fix RPM class: add package and full version properties

[VaaishnaviS]

Fixes #4684

Tasks

• Reviewed contribution guidelines
• PR is descriptively titled 📑 and links the original issue above 🔗
• Tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR
  Run tests locally to check for errors.
• Commits are in uniquely-named feature branch and has no merge conflicts 📁
• Updated documentation pages (if applicable)
• Updated CHANGELOG.rst (if applicable)

What was the issue:
In container image scans, RPM package versions were truncated. For example, instead of showing the full version like bash-4.4.20-4.el8_6, only bash-4.4.20 was displayed. This caused incomplete information for package analysis.

Changes made in this PR:

1. Preserved the existing behavior of rpm.package as name-version to avoid breaking existing expectations.
2. Added a new full_version property to explicitly return version-release, fixing truncated RPM versions in container image scans.
3. Fixed RPM filename generation to avoid duplicate inclusion of the release field.
4. Added a regression test in test_pyrpm.py to validate full_version and filename behavior.
5. Verified the changes by running the relevant pyrpm tests locally.

Signed-off-by: Vaishnavi S [email protected]