Updated query known and slsa parser

[Yaxhveer]

Description of the PR

Fixes #2016
Fixes #2015

Updated known command for hasSBOM to check for packages with attached artifacts having sboms.
Updated getSlsaEntity to use subjects uri as PURL.

PR Checklist

• All commits have a Developer Certificate of Origin (DCO) -- they are generated using -s flag to git commit.
• All new changes are covered by tests
• If GraphQL schema is changed, make generate has been run
• If GraphQL schema is changed, GraphQL client updates/additions have been made
• If OpenAPI spec is changed, make generate has been run
• If ent schema is changed, make generate has been run
• If collectsub protobuf has been changed, make proto has been run
• All CI checks are passing (tests and formatting)
• All dependent PRs have already been merged

[pxp928]

LGTM, minor nit and adding a unit test.

[pxp928]

LGTM! Thank You!