UI: chat composer step 2 (#21641)

- few improved alignments
- displays emoji picker button inline on desktop
- keeps composer focused when focusing dropdown button
- align buttons to bottom when increasing height of textarea
- max-height of textarea is now linked to the height of the screen

Co-authored-by: chapoi <charlie@discourse.org>

plugins/chat/test/javascripts/components/chat-composer-inline-buttons-test.js

@@ -1,23 +0,0 @@
-import { setupRenderingTest } from "discourse/tests/helpers/component-test";
-import { exists } from "discourse/tests/helpers/qunit-helpers";
-import hbs from "htmlbars-inline-precompile";
-import { module, test } from "qunit";
-import { render } from "@ember/test-helpers";
-
-module(
-  "Discourse Chat | Component | chat-composer-inline-buttons",
-  function (hooks) {
-    setupRenderingTest(hooks);
-
-    test("buttons", async function (assert) {
-      this.set("buttons", [{ id: "foo", icon: "times", action: () => {} }]);
-
-      await render(
-        hbs`<ChatComposerInlineButtons @buttons={{this.buttons}} />`
-      );
-
-      assert.true(exists(".chat-composer-inline-button.foo"));
-      assert.true(exists(".chat-composer-inline-button.foo .d-icon-times"));
-    });
-  }
-);