Enable providing icons for Android desktop notifications

Enable providing icons for Android desktop notifications

* doc/lispref/os.texi (Desktop Notifications)
<android-notifications-notify>: Mention the :icon parameter.

* java/org/gnu/emacs/EmacsDesktopNotification.java
(EmacsDesktopNotification) <icon>: New field.
(<init>): New argument ICON.  Set this.icon to its value.
(display1): Use provided icon and always supply a pending intent
to open Emacs once the notification is clicked.

* java/res/layout/sdk8_notifications_view.xml
(sdk8_notifications_title, sdk8_notifications_content): Set
foreground color to #000000.

* src/androidselect.c (android_init_emacs_desktop_notification):
Update signature of <init>.
(android_locate_icon): New function.
(android_notifications_notify_1): New arg ICON.
(Fandroid_notifications_notify): New parameter icon.
(syms_of_androidselect): <QCicon>: New symbol.