Remove the start decorator in favor of a command line option

tests/compiler/std/array.ts

@@ -1,8 +1,6 @@
 import { Array } from "array";
 import { COMPARATOR } from "util/sort";
 
-@start export function main(): void {}
-
 // Obtains the internal capacity of an array from its backing buffer.
 function internalCapacity<T>(array: Array<T>): i32 {
   // the memory region used by the backing buffer might still be larger in that the ArrayBuffer