Add contrast setting in dev options

See the attached video from b/266071578#comment2 to see how the setting
looks like.

Bug: 266071578
Test: atest ContrastDialogTest
Test: atest ContrastDialogControllerTest
Change-Id: Id9fc31a0562059814d4e342ea8095adc5b53d5f3

src/com/android/settings/theme/ContrastPreferenceController.kt

@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2023 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.settings.theme
+
+import android.app.UiModeManager
+import android.app.UiModeManager.ContrastUtils.CONTRAST_LEVEL_HIGH
+import android.app.UiModeManager.ContrastUtils.CONTRAST_LEVEL_MEDIUM
+import android.app.UiModeManager.ContrastUtils.toContrastLevel
+import android.content.Context
+import android.content.Intent
+import android.os.UserHandle
+import android.text.TextUtils
+import androidx.preference.Preference
+import com.android.internal.annotations.VisibleForTesting
+import com.android.settings.R
+import com.android.settings.core.BasePreferenceController
+
+/**
+ * Controller that opens the contrast dialog and updates the text describing the current contrast
+ */
+class ContrastPreferenceController(
+        private val context: Context,
+        private val uiModeManager: UiModeManager) : BasePreferenceController(context, KEY) {
+
+    companion object {
+        @VisibleForTesting
+        const val KEY = "contrast_preference"
+    }
+
+    override fun getAvailabilityStatus(): Int {
+        return AVAILABLE
+    }
+
+    override fun handlePreferenceTreeClick(preference: Preference): Boolean {
+        if (TextUtils.equals(preference.key, preferenceKey)) {
+            val intent = Intent(Intent.ACTION_SHOW_CONTRAST_DIALOG)
+            context.startActivityAsUser(intent, UserHandle(UserHandle.USER_CURRENT))
+            return true
+        }
+        return false
+    }
+
+    override fun getSummary(): CharSequence = getSummary(toContrastLevel(uiModeManager.contrast))
+
+    @VisibleForTesting
+    fun getSummary(contrast: Int): String {
+        return when (contrast) {
+            CONTRAST_LEVEL_HIGH -> context.getString(R.string.contrast_high)
+            CONTRAST_LEVEL_MEDIUM -> context.getString(R.string.contrast_medium)
+            else -> context.getString(R.string.contrast_standard)
+        }
+    }
+}