Bug 1864956 - Make Fenix a PDF reader

It makes possible to open a pdf coming from an other app, like a file
browser, in Fenix.

app/src/main/AndroidManifest.xml

@@ -252,6 +252,14 @@
                 <data android:scheme="https" />
             </intent-filter>
 
+            <intent-filter>
+                <action android:name="android.intent.action.VIEW" />
+                <category android:name="android.intent.category.BROWSABLE" />
+                <category android:name="android.intent.category.DEFAULT" />
+                <data android:mimeType="application/pdf" />
+                <data android:scheme="content" />
+            </intent-filter>
+
             <meta-data
                 android:name="com.android.systemui.action_assist_icon"
                 android:resource="@mipmap/ic_launcher" />