Add some aliases and fixes placeholder color.

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/theme/ColorAliases.kt

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2023 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.designsystem.theme
+
+import io.element.android.libraries.designsystem.SystemGrey4Dark
+import io.element.android.libraries.designsystem.SystemGrey6Light
+
+/**
+ * Room list
+ */
+val ElementColors.roomListRoomName get() = primary
+val ElementColors.roomListRoomMessage get() = secondary
+val ElementColors.roomListRoomMessageDate get() = secondary
+val ElementColors.roomListUnreadIndicator get() = primary
+val ElementColors.roomListPlaceHolder get() = if (isLight) SystemGrey6Light else SystemGrey4Dark