Second screen track pad implementation

[JoshRacine]

Touchpad Mode for Secondary Displays + 3-Finger Keyboard Fix

What's New

This PR adds a touchpad mode for dual-screen setups and fixes the annoying issue where the 3-finger keyboard gesture
would flash and immediately close.

Touchpad Mode Feature

• Added a new mode that turns your secondary display into a touchpad while the game streams to your primary display
• Uses Android's Presentation API to properly handle secondary displays
• Added a preference to select which display to use as the touchpad
• Added a quick menu option to toggle the touchpad on/off without restarting the stream (only shows up when touchpad
  mode is enabled in settings)
• The touchpad screen has buttons for keyboard, menu, and close
• Handles all the edge cases: activity lifecycle, screen rotation, display disconnection, etc.

3-Finger Keyboard Gesture Fix

This has been broken in Artemis for a while - when you'd do the 3-finger tap, the keyboard would appear for a split
second and vanish.

What was wrong:

• The StreamContainer wasn't telling Android it could accept text input, so the keyboard would bail immediately
• Text was being buffered until you pressed Enter instead of typing live

What's fixed:

• Keyboard now stays open when you tap with 3 fingers
• Characters type immediately as you press them (no more Enter key needed)
• Backspace works properly
• Back button dismisses the keyboard like it should
• Works regardless of the "enable commit text" preference setting

Files Changed

Modified:

• Game.java - Touchpad management, toggle methods
• GameMenu.java - Added touchpad toggle to main menu
• StreamContainer.java - Fixed keyboard input handling
• PreferenceConfiguration.java - Touchpad preferences
• ServerHelper.java - Display routing for touchpad mode
• ExternalDisplayControlActivity.java - Touchpad integration
• preferences.xml, strings.xml, arrays.xml - UI resources

Added:

• TouchpadPresentation.java - Touchpad UI for secondary display
• DisplaySelectionPreference.java - Display picker preference widget

Testing

Tested on AYN Thor (dual-screen handheld) with touchpad mode enabled/disabled, 3-finger gesture, keyboard input,
display disconnects, and app lifecycle stuff.

Compatibility

Everything is backwards compatible. Touchpad mode is optional and off by default. The keyboard fix just makes the
existing 3-finger gesture actually work.

[ClassicOldSong]

Thanks for your contribution but this actually conflicts with another PR which makes full external display mode work like your description: #437

[junoxxx67]

can i get some apk file?
this 3 finger keyboard fix...
my ayn thor cant use 3 finger keyboard..