Implement basic execution system and UI

This is a rather large commit that includes all of the following:
- React UI with code editor, runtime renderer and input-output panes
- Language providers for a sample language and Brainfuck
- Implementation of code execution in a web worker
- All-at-once unabortable execution of program fully functional

engines/sample-lang/index.ts

@@ -0,0 +1,10 @@
+import { Renderer } from "./renderer";
+import { LanguageProvider } from "../types";
+import { RS, sampleProgram } from "./constants";
+
+const provider: LanguageProvider<RS> = {
+  Renderer,
+  sampleProgram,
+};
+
+export default provider;