Remove building scene, add code execution loading indicator to bottom-right controls (#3691)

* Remove isFirstRender because isExecuting means the same and remove building scene

* add small makefile util

* Remove waiting for building scene prompt

* Add a new model state indicator

* fmt lint tsc

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Co-authored-by: Frank Noirot <frank@kittycad.io>

src/lang/KclSingleton.ts

@@ -60,8 +60,6 @@ export class KclManager {
   private _wasmInitFailedCallback: (arg: boolean) => void = () => {}
   private _executeCallback: () => void = () => {}
 
-  isFirstRender = true
-
   get ast() {
     return this._ast
   }