Show errors for invalid SBoM reports in the UI
## Why are we doing this work
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With https://gitlab.com/gitlab-org/gitlab/-/issues/364709, we added the ability for GitLab to ingest CycloneDX SBoMs.
Currently, SBoMs are validated and the warnings + errors from schema validation are collected, but there is no
way to show those errors to the end user.
### Proposal
See proposal in https://gitlab.com/gitlab-org/gitlab/-/issues/366960#proposal
**Note:** It's important to keep in mind that this is only available for workflows based on the default branch of the project. Storing SBOM reports error is tied to the SBOM report ingestion process (storing results in the Gitlab's PostgreSQL DB), which only happens on the default branch.
epic