[fenix] For https://github.com/mozilla-mobile/fenix/issues/26280: Add monochromatic themed app icon

Since Google has been pushing Themed app icons a new icon is needed
to adapt to the new styling.

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

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="108dp"
+    android:height="109dp"
+    android:viewportWidth="108"
+    android:viewportHeight="109">
+  <group>
+    <clip-path
+        android:pathData="M25.75,25.93h56.5v58.25h-56.5z"/>
+    <path
+        android:pathData="M80.22,45.46C78.99,42.51 76.5,39.33 74.54,38.32C75.94,41.01 76.9,43.9 77.41,46.89L77.41,46.93C74.21,38.98 68.79,35.78 64.36,28.79C64.13,28.43 63.91,28.07 63.69,27.71C63.58,27.52 63.48,27.33 63.38,27.13C63.2,26.77 63.06,26.4 62.96,26.01C62.96,25.99 62.95,25.98 62.94,25.96C62.93,25.95 62.91,25.94 62.89,25.94C62.88,25.93 62.86,25.93 62.84,25.94C62.84,25.94 62.83,25.94 62.83,25.95C62.82,25.95 62.81,25.95 62.81,25.96L62.82,25.94C56.53,29.61 53.92,36.05 53.25,40.14C51.31,40.25 49.4,40.74 47.64,41.57C47.47,41.65 47.34,41.8 47.27,41.98C47.21,42.16 47.22,42.36 47.3,42.53C47.38,42.71 47.52,42.84 47.7,42.91C47.88,42.97 48.08,42.96 48.25,42.88C49.79,42.16 51.44,41.73 53.13,41.61L53.3,41.6C53.53,41.59 53.76,41.58 53.99,41.57C55.37,41.56 56.73,41.75 58.05,42.14C58.13,42.16 58.21,42.18 58.28,42.21C58.5,42.28 58.72,42.35 58.94,42.43C59.09,42.49 59.25,42.55 59.4,42.61C59.53,42.66 59.66,42.71 59.78,42.77C59.98,42.85 60.17,42.94 60.36,43.04C60.45,43.08 60.54,43.12 60.62,43.17C60.81,43.27 60.99,43.37 61.17,43.47C61.29,43.54 61.41,43.61 61.52,43.68C63.57,44.94 65.27,46.7 66.47,48.79C64.47,47.41 62.05,46.82 59.65,47.13C69.83,52.21 67.09,69.68 52.99,69.02C51.74,68.97 50.5,68.73 49.31,68.32C49.04,68.21 48.76,68.1 48.48,67.98C48.32,67.91 48.16,67.83 48.01,67.75C44.55,65.97 41.7,62.6 41.34,58.51C41.34,58.51 42.65,53.66 50.69,53.66C51.56,53.66 54.05,51.24 54.1,50.54C54.09,50.31 49.16,48.35 47.24,46.47C46.22,45.46 45.73,44.97 45.3,44.61C45.07,44.41 44.82,44.23 44.57,44.06C43.92,41.81 43.89,39.42 44.49,37.16C41.88,38.42 39.56,40.2 37.68,42.41H37.67C36.54,40.99 36.62,36.32 36.68,35.34C36.35,35.47 36.03,35.64 35.74,35.84C34.75,36.54 33.82,37.34 32.97,38.2C32.01,39.18 31.12,40.24 30.33,41.37V41.37V41.37C28.51,43.94 27.22,46.84 26.53,49.92C26.35,50.78 26.19,51.64 26.07,52.52C26.04,52.74 26.01,52.96 25.98,53.18C25.9,53.72 25.85,54.25 25.82,54.79C25.82,54.82 25.82,54.85 25.81,54.88C25.79,55.19 25.77,55.5 25.75,55.82V55.96C25.82,63.05 28.51,69.86 33.3,75.06C38.1,80.25 44.65,83.47 51.67,84.06C58.7,84.66 65.7,82.6 71.29,78.28C76.88,73.97 80.68,67.71 81.92,60.74C81.97,60.37 82.01,60.01 82.05,59.64C82.63,54.84 82,49.96 80.21,45.47L80.22,45.46Z"
+        android:fillColor="#20123A"/>
+  </group>
+</vector>

app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -5,4 +5,5 @@
 <adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
     <background android:drawable="@color/ic_launcher_background"/>
     <foreground android:drawable="@drawable/ic_launcher_foreground"/>
+    <monochrome android:drawable="@drawable/ic_launcher_monochrome"/>
 </adaptive-icon>

app/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml

@@ -5,4 +5,5 @@
 <adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
     <background android:drawable="@color/ic_launcher_background"/>
     <foreground android:drawable="@drawable/ic_launcher_foreground"/>
+    <monochrome android:drawable="@drawable/ic_launcher_monochrome"/>
 </adaptive-icon>