XRAY-146488 - Onboarding pip env

[gauriy-tech]

• The pull request is targeting the dev branch.
• The code has been validated to compile successfully by running go vet ./....
• The code has been formatted properly using go fmt ./....
• All static analysis checks passed.
• All tests have passed. If this feature is not already covered by the tests, new tests have been added.
• Updated the Contributing page / ReadMe page / CI Workflow files if needed.
• All changes are detailed at the description. if not already covered at JFrog Documentation, new documentation have been added.

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Onboards pipenv as a supported package manager for jf curation-audit, following the same repo-detection and curation pass-through pattern already used for Poetry. Curation is resolved via a 3-tier priority: jf pipenv-config → ~/.pip/pip.conf index-url → Pipfile [[source]] — covering both JFrog-native setup and the common case where a customer already configured Artifactory as their PyPI index via pip.conf.

Changes
Add techutils.Pipenv to curation-audit's supported technologies, with a minimum-version gate (pipenv >= 2023.7.4) required for reliable --pypi-mirror support.
Add setRepoFromPipfile (3-tier repo detection) and wire it into SetRepo/auditTree.
Add installPipenvDeps, runPipenvInstallFromRemoteRegistry, and buildPipenvDownloadUrlsMap to resolve dependency download URLs and run pipenv install through the curation pass-through endpoint, rewriting the Pipfile's [[source]] URL when present.
Reuse existing CVS/403-blocked detection and fallback handling (same as Pip/Poetry).
Update CLI help text to list pipenv/poetry/pnpm as supported package managers.
Add unit tests for version parsing, repo detection (pip.conf/Pipfile), Pipfile.lock parsing, and CVS/403 detection.