-Path and -Specification should be usable together to override prereleases

### Story
```
As a ModuleFast user, I want to be able to install *specific* prerelease versions of some of my requirements that might be in a #Requires .ps1 or .psd1 manifest
```

the `#Requires` and `ModuleRequires` do not support prerelease versions to be defined. Currently `-PreRelease` can be used as a blunt hammer, but we should support specifying -Specifications that take precedence over what is in the #Requires file