Is a configuration management tool (Chef/Puppet/Ansible) necessary for managing an application on a PAAS system (Azure app service, Heroku, Elastic Beanstalk)? How would it be utilized? While a tool such as Chef does not inherently work on a PAAS system, there are other tools (such as Habitat) that can support this functionality. What kind of steps would it take to integrate these technologies?
A configuration management tool is not required to manage a PAAS. For example, when one has created a VM on Azure then it is possible to export the configuration snippet as powershell or as yaml and use yaml to deploy and manage systems.
In my opinion one should restrict configuration management tools like puppet or ansible to manage configuration files and installing additional packages and yaml to manage the PAAS as I prefer KISS.
If one would like to manage different PASS then one could consider to use terraform.
Modern configuration management tools can do a wide variety of things, so you can certainly use them to manage a PaaS. But it makes more sense to use a tool like Terraform to handle provisioning, since that's its specialty.