Add termux-notification & termux-notification-remove

[hugmouse]

API: https://wiki.termux.com/wiki/Termux-notification

Description: Display a system notification. Content text is specified using -c/--content or read from stdin.

Options:

--action action          action to execute when pressing the notification
 --alert-once             do not alert when the notification is edited
 --button1 text           text to show on the first notification button
 --button1-action action  action to execute on the first notification button
 --button2 text           text to show on the second notification button
 --button2-action action  action to execute on the second notification button
 --button3 text           text to show on the third notification button
 --button3-action action  action to execute on the third notification button
 -c/--content content     content to show in the notification. Will take precedence over stdin.
 --group group            notification group (notifications with the same group are shown together)
 -h/--help                show this help
 --help-actions           show the help for actions
 -i/--id id               notification id (will overwrite any previous notification with the same id)
 --image-path path        absolute path to an image which will be shown in the notification
 --led-color rrggbb       color of the blinking led as RRGGBB (default: none)
 --led-off milliseconds   number of milliseconds for the LED to be off while it's flashing (default: 800)
 --led-on milliseconds    number of milliseconds for the LED to be on while it's flashing (default: 800)
 --on-delete action       action to execute when the the notification is cleared
 --ongoing                pin the notification
 --priority prio          notification priority (high/low/max/min/default)
 --sound                  play a sound with the notification
 -t/--title title         notification title to show
 --vibrate pattern        vibrate pattern, comma separated as in 500,1000,200
 --type type              notification style to use (default/media)

Media actions (available with --type "media"):

 --media-next             action to execute on the media-next button
 --media-pause            action to execute on the media-pause button
 --media-play             action to execute on the media-play button
 --media-previous         action to execute on the media-previous button

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API: https://wiki.termux.com/wiki/Termux-notification-remove

Description: Remove a notification previously shown with "termux-notification --id".

Options: none