BREAKING: remove deno vendor

[iuioiua]

deno vendor now produces:

error: ⚠️ `deno vendor` was removed in Deno 2.

See the Deno 1.x to 2.x Migration Guide for migration instructions: https://docs.deno.com/runtime/manual/advanced/migrate_deprecations

deno vendor --help now produces:

⚠️ `deno vendor` was removed in Deno 2.

See the Deno 1.x to 2.x Migration Guide for migration instructions: https://docs.deno.com/runtime/manual/advanced/migrate_deprecations

Usage: deno vendor [OPTIONS]

Options:
  -q, --quiet     Suppress diagnostic output
      --unstable  Enable all unstable features and APIs. Instead of using this flag, consider enabling individual unstable features
                    To view the list of individual unstable feature flags, run this command again with --help=unstable

Towards #22079