Group modeled methods by library in the data extensions editor

[koesie10]

This groups the modeled methods in the data extensions editor by library:

For now, it's sorted by name. Follow-up PRs will change this to be based on other factors, such as usages and the modeled percentage.

Checklist

• CHANGELOG.md has been updated to incorporate all user visible changes made by this pull request.
• Issues have been created for any UI or other user-facing changes made by this pull request.
• [Maintainers only] If this pull request makes user-facing changes that require documentation changes, open a corresponding docs pull request in the github/codeql repo and add the ready-for-doc-review label there.

[starcke]

We probably want other functionality (like collapsing) and to sort differently, but I think this is a great start.