Allow Enriching in Air-Gapped Environment

No internet means CISA KEV information cannot be pulled in to enrich the data being visualized. That URL is hardcoded at
https://github.com/CycloneDX/Sunshine/blob/67ea8bec90ce109efbabea29be4894ce435537d2/sunshine.py#L1851

But `https://lucacapacci.github.io/cisa_kev/data_groups/` could instead be a default, and be overridden via command-line argument or environment variable so that the script instead looks at a local filepath or a self-hosted file storage endpoint.

There should just be a way to substitute `https://lucacapacci.github.io` with something custom.

Start in sunshine.py at line 1851, where the CISA KEV URL is hardcoded, and inspect how command-line arguments and environment variables are handled. The work is done when the default endpoint remains usable and users can substitute a local filepath or self-hosted endpoint for https://lucacapacci.github.io.

Written by the indexing model from the issue text.