Tab5 ST7121 variant + fixes (#605)

Added the newest variant to the tab5, St7121.
Fixed variant detection reliability
Fixed tab5 camera WHO_AM_I failing sometimes
Fixed tab5 keyboard live rotation on boot and after stopping/starting lvgl

Devices/m5stack-tab5/Source/devices/tab5_keyboard_attach_detect.h

@@ -0,0 +1,12 @@
+#pragma once
+
+// Starts/stops the periodic keyboard-accessory hot-plug poll: reapplies register configuration on
+// reattach (see tab5_keyboard_reinit()) and switches LVGL to landscape while attached, restoring
+// the prior rotation on detach - unless the user changed it manually since attaching, in which
+// case their choice is respected. Also re-announces the current attach state after LVGL itself
+// restarts (e.g. an app that took over the display for direct rendering, stopping and letting
+// LVGL rebind), since that's a distinct event from the keyboard physically attaching/detaching -
+// the accessory may never have moved, but the rotation override it applied may have been reset in
+// the meantime. Called from module.cpp's start()/stop().
+void tab5_keyboard_attach_detect_start();
+void tab5_keyboard_attach_detect_stop();