Add support for installing other distributions - Drupal core, Commerce Kickstart

Problem/Motivation

When installing other distributions like Drupal Core or Commerce Kickstart, you run into different problems for each.

With Drupal Core, the installer mostly works, but at the end of the site:install, Drush is re-adding the database stanza to the settings.php after the nix include, which breaks it.

This is already solved for the CMS installer (by creating a temp copy of the original settings.php before the install, and copying it over settings.php after the install). Make this work with other installers.

For Commerce Kickstart, Drush does not have a binary in vendor/bin -- the Kickstart profile is setting bin/ as the location for vendor binaries instead.

Steps to reproduce

Proposed resolution

Improve the installer to handle specific issues around different starting points.

Improve the AI skill to provide assistance installing different Drupal distributions.

Remaining tasks

User interface changes

API changes

Data model changes