Deleting a project should delete it's environments

Describe the bug

At the moment, in order to delete an entire project, you are expected to delete its environments first. Failure to do so will result in orphaned environments in the api-db database that you cannot remove with GraphQL. It will also mean that the projects continue to run in OpenShift/Kubernetes with no hope of removing them, except manual intervention with oc/kubectl.

To Reproduce

Steps to reproduce the behaviour:

1. Create project
2. Create environment for above project
3. Delete project
4. Now you cannot delete the environment as the project is deleted

Expected behaviour

2 parts

1. If you delete a project, it should loop through all of it’s environments and delete them. Potentially, this is just a matter of amending the stored procedure.
2. Create a new stored procedure and API endpoint to allow deleting an environment by it’s ID (rather than project name and environment name).

[shreddedbacon]

We could do it in the CLI, but it would mean that people would have to update their CLI to get this feature.

I proposed the following solution for the API in the CLI issue related to this https://github.com/amazeeio/lagoon-cli/issues/117#issuecomment-611864789

It makes more sense for the API to handle these sorts of things than hacking it into the CLI

[tobybellwood]

Enviroinments should be deleted before deleting a project. There are now checks for this.