Add environment(s) for celestials and fiends

[mlenser]

Maybe Upper Planes and Lower Planes.

Maybe other creatures should have environments like Plane of Water or other similar cases.

[mlenser]

• Added Upper planes environment to Celestials. #920
• Added Lower planes environment to Fiends. #920
• Added Elemental planes environment to Elementals. #920
• All creatures now have an environment. #920

[mlenser]

Also added the Far Realm Feywild, Limbo, and Shadowfell.