reorg: remove dispatch.ts, move signals, factor out web utils (#4316)

- moves signal definition from "cli/js/process.ts" to "cli/js/signals.ts"
- removes "cli/js/dispatch.ts"
- removes "cli/js/types.ts"
- moves web specific utilities to "cli/js/web/util.ts"

cli/js/runtime_main.ts

@@ -18,7 +18,7 @@ import {
   eventTargetProperties
 } from "./globals.ts";
 import { internalObject } from "./internals.ts";
-import { setSignals } from "./process.ts";
+import { setSignals } from "./signals.ts";
 import { replLoop } from "./repl.ts";
 import * as runtime from "./runtime.ts";
 import { symbols } from "./symbols.ts";