icon: add regular png icon for compatibility with some launchers

See termux#991.

Adaptive icon will continue to be automatically used if supported.

Author: Leonid Pliushch

app/src/main/AndroidManifest.xml

@@ -11,7 +11,7 @@
     <permission android:name="com.termux.permission.RUN_COMMAND"
         android:label="@string/run_command_permission_label"
         android:description="@string/run_command_permission_description"
-        android:icon="@drawable/ic_launcher"
+        android:icon="@mipmap/ic_launcher"
         android:protectionLevel="dangerous" />
 
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
@@ -28,7 +28,8 @@
     <application
         android:extractNativeLibs="true"
         android:allowBackup="false"
-        android:icon="@drawable/ic_launcher"
+        android:icon="@mipmap/ic_launcher"
+        android:roundIcon="@mipmap/ic_launcher_round"
         android:banner="@drawable/banner"
         android:label="@string/application_name"
         android:theme="@style/Theme.Termux"

app/src/main/res/drawable/ic_launcher.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@android:color/black"/>
+    <foreground android:drawable="@drawable/ic_foreground"/>
+</adaptive-icon>