feat: convert mismatch utility into a standalone entity

[inosmeet]

• mismatch -> this command will run the loader and load the default database with default data.
• mismatch loader [--dir] [--database] -> same as previous but with ability to define custom data directory and database file.
• mismatch lookup PURL [--database] -> takes PURL as an argument and returns vendor names associated from database and error if nothing is found.

default values for --dir and --database is tailored for cve-bin-tool, but I think if we were to make it truly standalone, we should make those flags compulsory.

cc @terriko

[terriko]

This looks like exactly what we need, but I'd rather not add a new dependency (click) unless we absolutely have to, both for security reasons and because going through our legal licensing compliance for a new dependency adds a lot of time and overhead.

Can you convert this to just use argparse instead?

[terriko]

Looks good! I'll open an issue reminding you to get docs and tests for this done in a separate PR.