Add the ability to disable composer install during deployment.

[Graloth]

Currently with the drupal role, it's assumed that if there is a composer.json, and the codebase is being deployed via Git(drupal_deploy: true), then composer install should be run

• Reference: How to prevent drupal-vm from running composer install? drupal-vm#1500 (comment)

My current need is to be able to disable the use of composer install when deploying from git, as I need to make some edits to my current composer.json file before manually running it (I am working on getting the composer.json working, but it's a complex project with a lot of custom code).

A config option, such as drupal_composer_install_after_deploy that could be set to true/false or yes/no would be great.

[geerlingguy]

I, uh, need this now. So I'll do it now :D