feat(gs/xanthous): Add a Husk creature, with limited generation

Add a new "husk" creature raw, limited to only being generated on levels
>= 1, including support for actually doing that limiting.

These guys are gonna get daggers next!

Change-Id: Ic4b58dc7ee36b50ced60fec6912cd1b46269d55c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3868
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI

users/grfn/xanthous/test/Xanthous/Entities/RawTypesSpec.hs

@@ -0,0 +1,28 @@
+--------------------------------------------------------------------------------
+module Xanthous.Entities.RawTypesSpec (main, test) where
+--------------------------------------------------------------------------------
+import           Test.Prelude
+--------------------------------------------------------------------------------
+import           Xanthous.Entities.RawTypes
+--------------------------------------------------------------------------------
+
+main :: IO ()
+main = defaultMain test
+
+test :: TestTree
+test = testGroup "Xanthous.Entities.RawTypesSpec"
+  [ testGroup "CreatureGenerateParams"
+    [ testBatch $ monoid @CreatureGenerateParams mempty
+    , testGroup "canGenerate"
+      [ testProperty "no bounds" $ \level ->
+          let gps = CreatureGenerateParams Nothing Nothing
+          in canGenerate level gps
+      , testProperty "min bound" $ \level minB ->
+          let gps = CreatureGenerateParams (Just minB) Nothing
+          in canGenerate level gps === (level >= minB)
+      , testProperty "max bound" $ \level maxB ->
+          let gps = CreatureGenerateParams Nothing (Just maxB)
+          in canGenerate level gps === (level <= maxB)
+      ]
+    ]
+  ]