Add optional controller rumble on button press

New "Vibrate controller on button press" setting under Controls. When enabled,
pressing a gamepad button rumbles that pad for as long as it's held - something
the PSP hardware never had, but which some people want from a modern pad.

Implemented per platform behind System_ControllerRumbleStart/Stop: SDL uses
SDL_RumbleGamepad, Windows feeds it into XinputDevice's existing vibration path
so it doesn't fight with the vibration games request through sceCtrl, and
Android goes through InputDevice.getVibrator() in Java. Stubbed elsewhere.

The D-pad is excluded, since it gets tapped constantly while navigating.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01GgACRqkQNpfJQ4fjwyoEup

Core/Config.cpp

@@ -946,6 +946,7 @@ static const ConfigSetting touchControlSettings[] = {
 
 static const ConfigSetting controlSettings[] = {
 	ConfigSetting("HapticFeedback", SETTING(g_Config, bHapticFeedback), false, CfgFlag::PER_GAME),
+	ConfigSetting("ControllerButtonRumble", SETTING(g_Config, bControllerButtonRumble), false, CfgFlag::PER_GAME),
 	
 #if PPSSPP_PLATFORM(WINDOWS)
 	ConfigSetting("IgnoreWindowsKey", SETTING(g_Config, bIgnoreWindowsKey), false, CfgFlag::PER_GAME),