Use `list-api` when publishing and installing Composer packages

Problem to solve

V2 of Composer offers performance and usability improvements. This includes a new API endpoint, the list-api.

This is a new route that is considered optional for V2.

/api/v4/groups/:id/-/packages/composer/list.json?filter=<package_name>

It is essentially a search endpoint. Given a value for the filter param, which will allow * as a wildcard, it returns all packages in the group matching that name. See https://packagist.org/packages/list.json?filter=composer/* as an example. We should be able to implement this using our existing finder.

Proposal

Add support for list-api so that the GitLab registry supports all of the functionality in v2 of Composer.

Further details

MR Plan

1. Add the new route and update the finder for the filter param. The problem is that the GitLab Package Registry does not currently support using this field.