FIX: Emoji autocomplete “more” button not working in chat (#20113)

* FIX: Emoji autocomplete “more” button not working

* Rely on setting an intial value on the filter input

This commit removes custom logic applied on initial filter and instead gives a param to use as value for the input, automatically triggering the existing filtering handler.

Other notes:
- Slightly changes the API to be able to set a filter and open the composer in one go
- Adds a very simple service spec
- Adds a system spec to fully validate the behavior

---------

Co-authored-by: Joffrey JAFFEUX <j.jaffeux@gmail.com>

plugins/chat/test/javascripts/unit/services/chat-emoji-picker-manager-test.js

@@ -24,7 +24,7 @@ module(
 
     test("startFromMessageReactionList", async function (assert) {
       const callback = () => {};
-      this.manager.startFromMessageReactionList({ id: 1 }, false, callback);
+      this.manager.startFromMessageReactionList({ id: 1 }, callback);
 
       assert.ok(this.manager.loading);
       assert.ok(this.manager.opened);
@@ -44,7 +44,7 @@ module(
 
     test("startFromMessageActions", async function (assert) {
       const callback = () => {};
-      this.manager.startFromMessageReactionList({ id: 1 }, false, callback);
+      this.manager.startFromMessageReactionList({ id: 1 }, callback);
 
       assert.ok(this.manager.loading);
       assert.ok(this.manager.opened);
@@ -104,6 +104,14 @@ module(
       assert.strictEqual(this.manager.loading, false);
     });
 
+    test("startFromComposer with filter option", async function (assert) {
+      const callback = () => {};
+      this.manager.startFromComposer(callback, { filter: "foofilter" });
+      await settled();
+
+      assert.strictEqual(this.manager.initialFilter, "foofilter");
+    });
+
     test("closeExisting", async function (assert) {
       const callback = () => {
         return;