Stylua formatting (#785)

Uses Stylua to format all existing Lua files, and adds a CI check in
`lint` to pin this improvement. Excludes formatting dependencies, of
course.

plugin/src/PatchTree.lua

@@ -401,7 +401,9 @@ end
 
 -- Creates a deep copy of a tree for immutability purposes in Roact
 function PatchTree.clone(tree)
-	if not tree then return end
+	if not tree then
+		return
+	end
 
 	local newTree = Tree.new()
 	tree:forEach(function(node)