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/App/Components/CodeLabel.lua

@@ -22,7 +22,7 @@ function CodeLabel:didMount()
 end
 
 function CodeLabel:didUpdate()
-    self:updateHighlights()
+	self:updateHighlights()
 end
 
 function CodeLabel:updateHighlights()