[REF] web: remove useWidget compatibility helper

Now that the last Component using that helper have been fully
converted to Owl (AceEditorWrapper -> ResourceEditor), we can
remove it.

Part of task~3439226

Part-of: odoo/odoo#139154

addons/web/static/src/legacy/utils.js

@@ -1,16 +1,6 @@
 /** @odoo-module **/
 
-import {
-    App,
-    Component,
-    onMounted,
-    onWillStart,
-    onWillUnmount,
-    useEnv,
-    useRef,
-    useState,
-    xml,
-} from "@odoo/owl";
+import { App, Component, useState, xml } from "@odoo/owl";
 import { templates } from "@web/core/assets";
 import { _t } from "@web/core/l10n/translation";
 
@@ -41,26 +31,6 @@ export function createWidgetParent(env) {
     };
 }
 
-export function useWidget(refName, widgetClass, params = []) {
-    const ref = useRef(refName);
-    const env = useEnv();
-
-    const parent = createWidgetParent(env);
-    const widget = new widgetClass(parent, ...params);
-
-    onWillStart(() => {
-        return widget._widgetRenderAndInsert(() => {});
-    });
-    onMounted(() => {
-        ref.el.append(widget.el);
-    });
-    onWillUnmount(() => {
-        widget.destroy();
-    });
-
-    return widget;
-}
-
 const rootTemplate = xml`<SubComp t-props="state"/>`;
 export async function attachComponent(parent, element, componentClass, props = {}) {
     class Root extends Component {

addons/web/static/tests/legacy/owl_compatibility_tests.js

@@ -1,10 +1,8 @@
 /** @odoo-module **/
 
-    import { registry } from "@web/core/registry";
-    import { attachComponent, useWidget } from "@web/legacy/utils";
+    import { attachComponent } from "@web/legacy/utils";
 
-    import { makeTestEnv } from "@web/../tests/helpers/mock_env";
-    import { getFixture, mount } from "@web/../tests/helpers/utils";
+    import { getFixture } from "@web/../tests/helpers/utils";
     import Widget from "@web/legacy/js/core/widget";
     import {
         Component,
@@ -13,75 +11,11 @@
         onWillDestroy,
         onWillStart,
         onWillUpdateProps,
-        useRef,
-        useState,
         xml,
     } from "@odoo/owl";
     import { nextTick } from "./helpers/test_utils";
 
     QUnit.module("Owl Compatibility", function () {
-        QUnit.test("useWidget", async (assert) => {
-            assert.expect(9);
-
-            let widget = null;
-            const CustomWidget = Widget.extend({
-                init(_, ...params) {
-                    this._super(...arguments);
-                    widget = this;
-                    assert.step("widget initialized");
-                    assert.deepEqual(params, ["a", 1]);
-                    this.params = params;
-                },
-                start() {
-                    this.$el.text("Hello World!");
-                },
-                callTriggerUp() {
-                    this.call("test", "call", { [this.params[0]]: this.params[1] });
-                },
-            });
-
-            class ComponentAdapter extends Component {
-                static template = xml`<div id="adapter" t-ref="container"/>`;
-                setup() {
-                    this.containerRef = useRef("container");
-                    this.widget = useWidget("container", CustomWidget, ["a", 1]);
-                    assert.strictEqual(this.widget, widget);
-                }
-            }
-
-            class Toggle extends Component {
-                static components = { ComponentAdapter };
-                static template = xml`<ComponentAdapter t-if="state.active"/>`;
-                state = useState({ active: true });
-            }
-
-            const target = getFixture();
-            registry.category("services").add("test", {
-                start: () => ({
-                    call: (p) => {
-                        assert.step("triggered up");
-                        assert.deepEqual(p, { a: 1 });
-                    },
-                }), 
-            });
-            const component = await mount(Toggle, target, {
-                env: await makeTestEnv(),
-            });
-            assert.verifySteps(["widget initialized"]);
-
-            assert.strictEqual(
-                target.querySelector("#adapter").textContent,
-                "Hello World!"
-            );
-
-            widget.callTriggerUp();
-            assert.verifySteps(["triggered up"]);
-
-            component.state.active = false;
-            await nextTick();
-            assert.ok(widget.isDestroyed());
-        });
-
         QUnit.test("attachComponent", async (assert) => {
             assert.expect(13);