LLM-20426 Show dropdown icons for certain icons

Before this change we used to hide the dropdown icon for all popup action groups in CodeFloatingToolbar. However mockups for this feature require this dropdown to be present for the AI actions popup. This commit adds a ShowsDropdownIconInFloatingToolbar marker interface implementing which makes CodeFloatingToolbar show such icons.

GitOrigin-RevId: b25aed52ee236072ea818d5f31b2fe71eb362c1e

platform/platform-impl/src/com/intellij/ui/codeFloatingToolbar/CodeFloatingToolbar.kt

@@ -194,7 +194,9 @@ class CodeFloatingToolbar(
     val hint = super.createHint()
     val buttons = UIUtil.findComponentsOfType(hint.component, ActionButton::class.java)
     buttons.forEach { button ->
-      button.presentation.putClientProperty(ActionUtil.HIDE_DROPDOWN_ICON, true)
+      if (button.action !is ShowsDropdownIconInFloatingToolbar) {
+        button.presentation.putClientProperty(ActionUtil.HIDE_DROPDOWN_ICON, true)
+      }
       showMenuPopupOnMouseHover(button)
     }
     return hint

platform/platform-impl/src/com/intellij/ui/codeFloatingToolbar/ShowsDropdownIconInFloatingToolbar.kt

@@ -0,0 +1,8 @@
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.ui.codeFloatingToolbar
+
+/**
+ * By default [CodeFloatingToolbar] hides dropdown icons of popup action groups it contains.
+ * Implement this interface to show dropdown icons for your popup action group.
+ */
+interface ShowsDropdownIconInFloatingToolbar