Description of the problem, including code/CLI snippet

It would be nice to add a get() method to the ProjectEnvironment* classes. This is useful because currently simply calling project.environments.list() does not return all the information about a given environment, such as when it was last deployed.

Expected Behavior

There should be a project.environments.get(environment_id) method, using the environment_id as an argument, which then calls the endpoint here (https://docs.gitlab.com/ce/api/environments.html#get-a-specific-environment), or /projects/:id/environments/:environment_id.

Actual Behavior

Currently, no such method exists.

Specifications

• python-gitlab version: python-gitlab==1.10.0
• API version you are using (v3/v4): v4
• Gitlab server version (or gitlab.com): gitlab.com