add modifier keys in terminal app

Except ctrl key, it just generates a matched keycode to the view
ctrl key, it enables javascript variable `ctrl`, and handler inside
xtermjs reads ctrl variable and the keycode, and if it is convertible
to ctrl keycode, it does.

Test: test added keys
Bug: 376813452
Change-Id: I22e5f80ca75ffe6426b7374855cdd015ad08f324
diff --git a/android/TerminalApp/res/values/keyboard_btn_strings.xml b/android/TerminalApp/res/values/keyboard_btn_strings.xml
new file mode 100644
index 0000000..384c583
--- /dev/null
+++ b/android/TerminalApp/res/values/keyboard_btn_strings.xml
@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--  Copyright (C) 2024 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.
+ -->
+
+<resources xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
+    <string name="btn_esc_text" translatable="false">Esc</string>
+    <string name="btn_tab_text" translatable="false">Tab</string>
+    <string name="btn_home_text" translatable="false">Home</string>
+    <string name="btn_up_text" translatable="false">↑</string>
+    <string name="btn_end_text" translatable="false">End</string>
+    <string name="btn_pgup_text" translatable="false">PgUp</string>
+    <string name="btn_ctrl_text" translatable="false">Ctrl</string>
+    <string name="btn_alt_text" translatable="false">Alt</string>
+    <string name="btn_left_text" translatable="false">←</string>
+    <string name="btn_down_text" translatable="false">↓</string>
+    <string name="btn_right_text" translatable="false">→</string>
+    <string name="btn_pgdn_text" translatable="false">PgDn</string>
+</resources>
diff --git a/android/TerminalApp/res/values/styles.xml b/android/TerminalApp/res/values/styles.xml
new file mode 100644
index 0000000..ee80862
--- /dev/null
+++ b/android/TerminalApp/res/values/styles.xml
@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+     Copyright (C) 2024 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.
+-->
+<resources>
+    <style name="ModifierKeyStyle" parent="@style/Widget.Material3.Button.TextButton">
+        <item name="android:textAppearance">?android:attr/textAppearanceSmall</item>
+        <item name="android:textColor">?android:attr/textColorPrimary</item>
+        <item name="android:layout_weight">1</item>
+        <item name="android:layout_width">0dp</item>
+        <item name="android:layout_height">wrap_content</item>
+        <item name="android:paddingHorizontal">0dp</item>
+        <item name="android:hapticFeedbackEnabled">true</item>
+    </style>
+</resources>
\ No newline at end of file