Initial implementation of GPUBindGroupLayout for WebGPU

Added WebIDL bindings for `GPUBindGroupLayout`, `GPUBindGroupLayoutDescriptor`, `GPUBindingType`, `GPUShaderStage`
and `GPUBindGroupLayoutBinding` (Note: The servo's codegen doesn't like the name, because its already occupied).
Implemented the `createBindGroupLayout` function of `GPUDevice`.

components/script/dom/webidls/GPUBindGroupLayout.webidl

@@ -0,0 +1,34 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+// https://gpuweb.github.io/gpuweb/#gpubindgrouplayout
+[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom.webgpu.enabled"]
+interface GPUBindGroupLayout {
+};
+GPUBindGroupLayout includes GPUObjectBase;
+
+dictionary GPUBindGroupLayoutDescriptor : GPUObjectDescriptorBase {
+    required sequence<GPUBindGroupLayoutBindings> bindings;
+};
+
+// Note: Servo codegen doesn't like the name `GPUBindGroupLayoutBinding` because it's already occupied
+// dictionary GPUBindGroupLayoutBinding {
+dictionary GPUBindGroupLayoutBindings {
+    required unsigned long binding;
+    required GPUShaderStageFlags visibility;
+    required GPUBindingType type;
+    //GPUTextureViewDimension textureDimension = "2d";
+    //GPUTextureComponentType textureComponentType = "float";
+    boolean multisampled = false;
+    boolean hasDynamicOffset = false;
+};
+
+enum GPUBindingType {
+    "uniform-buffer",
+    "storage-buffer",
+    "readonly-storage-buffer",
+    "sampler",
+    "sampled-texture",
+    "storage-texture"
+};