Migrate classic buildpack to artifact inventory code

The changes in https://github.com/heroku/buildpacks-nodejs/pull/814 intentionally skipped these files used exclusively by the classic buildpack:

* https://github.com/heroku/buildpacks-nodejs/blob/main/common/nodejs-utils/src/bin/generate_inventory.rs
* https://github.com/heroku/buildpacks-nodejs/blob/main/common/nodejs-utils/src/bin/resolve_version.rs

Migrating these is a blocker to allowing the classic buildpack to support ARM64: https://github.com/heroku/heroku-buildpack-nodejs/issues/1268

The `generate_inventory` script appears to have been superseded by the `update_node_inventory`, but this does not work on the classic buildpack because it expects the Changelog entries to follow strict semver, which [it does not](https://github.com/heroku/heroku-buildpack-nodejs/blob/main/CHANGELOG.md#v266---2024-10-04).

Start with common/nodejs-utils/src/bin/generate_inventory.rs and common/nodejs-utils/src/bin/resolve_version.rs, then compare them with update_node_inventory. Review the classic buildpack's CHANGELOG.md, including the non-strict-semver entry, to understand the migration constraint. Done means the classic buildpack uses the artifact inventory flow and no longer blocks ARM64 support.

Written by the indexing model from the issue text.