[WIP] Start implementing execution in the new TS version

src/vm/commands/clear.ts

@@ -1,5 +1,7 @@
 import {Command, ParseContext} from "./command.js";
 import {LexInput} from "../lexer.js";
+import {StrVM} from "../vm.js";
+import {Awaitable} from "../../util/types.js";
 
 export class Clear extends Command<{}> {
     isParseCandidate(token: LexInput): boolean {
@@ -13,4 +15,10 @@ export class Clear extends Command<{}> {
     getDisplayName(): string {
         return 'clear'
     }
+
+    execute(vm: StrVM): Awaitable<StrVM> {
+        return vm.inPlace(ctx =>
+            ctx.replaceSubject(sub =>
+                sub.replaceWith('')))
+    }
 }