Add capability to remove existing conflicting module versions to PSGallery

[aromano2]

In order to maintain a desired state for your module environment, there needs to be a way to clean out any unexpected module version conflicts. For example, if I already have Pester v4.1.0 installed on my machine and want to additionally define a dependency with v4.9.0, I would want PSDepend to allow me to delete the old v4.1.0 automatically.