BREAKING(unstable): remove WebGPU (#18094)

This PR _**temporarily**_ removes WebGPU (which has behind the
`--unstable` flag in Deno), due to performance complications due to its
presence.

It will be brought back in the future; as a point of reference, Chrome
will ship WebGPU to stable on 26/04/2023.

---------

Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>

cli/tsc/dts/lib.deno.window.d.ts

@@ -3,7 +3,6 @@
 /// <reference no-default-lib="true" />
 /// <reference lib="deno.ns" />
 /// <reference lib="deno.shared_globals" />
-/// <reference lib="deno.webgpu" />
 /// <reference lib="deno.webstorage" />
 /// <reference lib="esnext" />
 /// <reference lib="deno.cache" />
@@ -94,7 +93,6 @@ declare var caches: CacheStorage;
 /** @category Web APIs */
 declare class Navigator {
   constructor();
-  readonly gpu: GPU;
   readonly hardwareConcurrency: number;
   readonly userAgent: string;
   readonly language: string;

cli/tsc/dts/lib.deno.worker.d.ts

@@ -3,7 +3,6 @@
 /// <reference no-default-lib="true" />
 /// <reference lib="deno.ns" />
 /// <reference lib="deno.shared_globals" />
-/// <reference lib="deno.webgpu" />
 /// <reference lib="esnext" />
 /// <reference lib="deno.cache" />
 
@@ -58,7 +57,6 @@ declare class WorkerGlobalScope extends EventTarget {
 /** @category Web APIs */
 declare class WorkerNavigator {
   constructor();
-  readonly gpu: GPU;
   readonly hardwareConcurrency: number;
   readonly userAgent: string;
   readonly language: string;