This PR exports an (auto) migrated version (using oxlint-migrate) of the default unjs preset to the package to reuse across projects (we use this preset in most of unjs repos, h3 and nitro).

Notes:

• Not sure yet, even if we can extend oxlint config, have to try, or do a ln -s node_modules/eslint-config-unjs/.oxlintrc.json .
• Globals and $schema removed to reduce size (also not sure)
• Had to patch jiti usage in oxlint-migrate, consistent with Node.js ESM, defaults should be interoperable otherwise even imports from eslint package are broken (we extend config from src/index.ts`
• Final JSON is pre-formatted via oxfmt! (as JSON.stringify is not compliant with prettier/oxfmt, even linking to project root triggers fromatter)

/cc @Boshen