Add a square brush and wire up the HUD brush preview

Add the BrushesSquare texture, replace the duplicated brush slots on the
player with it, show a brush preview in the paint HUD, and surface the
spawn-area tags and conversion reveal delay in the inspector.

Assets/Prefabs/Player.prefab

@@ -298,6 +298,11 @@ MonoBehaviour:
   ShowTopMostFoldoutHeaderGroup: 1
   spawnRingRadius: 0.5
   spawnRingSlots: 8
+  hunterSpawnAreaTag: HunterSpawnArea
+  hiderSpawnAreaTag: HiderSpawnArea
+  spawnAreaTag: SpawnArea
+  spawnAreaGroundLift: 1
+  conversionRevealDelay: 0.2
   role: 0
   scopedModes: 0
 --- !u!114 &8646586982149381366
@@ -494,9 +499,7 @@ MonoBehaviour:
   - {fileID: 2800000, guid: d07c01c40cc7be54da0ff3ae52484cd2, type: 3}
   - {fileID: 2800000, guid: ccc205272b051834eb39593f647c7bf1, type: 3}
   - {fileID: 2800000, guid: 04bc55e2853356e4f999b995d0066b33, type: 3}
-  - {fileID: 2800000, guid: 25780adbe09da488ba079bc33c4bbf0f, type: 3}
-  - {fileID: 2800000, guid: 25780adbe09da488ba079bc33c4bbf0f, type: 3}
-  - {fileID: 2800000, guid: 25780adbe09da488ba079bc33c4bbf0f, type: 3}
+  - {fileID: 2800000, guid: 9da705c8378866146a1d4be7b2469378, type: 3}
   activeBrushIndex: 0
   brushAlignment: 0
   brushRotation: 0