Adds Text to the common module.

UserSwitcherActivity refactor: CL 2/7

Following the precedent set by Icon and ContentDescription, Text is a
sealed class that can represent a string that is either already loaded
into memory or is referenced to using a resource ID.

This CL also includes the TextViewBinder.

Bug: 243844359
Test: Manually tested as part of CL 7/7 in the chain
Change-Id: I85bc6866fff9d37e573d4cdeaa74da8efbb35246

packages/SystemUI/src/com/android/systemui/common/shared/model/Text.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * 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 com.android.systemui.common.shared.model
+
+import android.annotation.StringRes
+
+/**
+ * Models a text, that can either be already [loaded][Text.Loaded] or be a [reference]
+ * [Text.Resource] to a resource.
+ */
+sealed class Text {
+    data class Loaded(
+        val text: String?,
+    ) : Text()
+
+    data class Resource(
+        @StringRes val res: Int,
+    ) : Text()
+}

packages/SystemUI/src/com/android/systemui/common/ui/binder/TextViewBinder.kt

@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * 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 com.android.systemui.common.ui.binder
+
+import android.widget.TextView
+import com.android.systemui.common.shared.model.Text
+
+object TextViewBinder {
+    fun bind(view: TextView, viewModel: Text) {
+        view.text =
+            when (viewModel) {
+                is Text.Resource -> view.context.getString(viewModel.res)
+                is Text.Loaded -> viewModel.text
+            }
+    }
+}