feat: add MIDI 2.0 Device class driver (USB-MIDI 2.0)

Add native USB-MIDI 2.0 Device class driver to TinyUSB. Implements the
USB-MIDI 2.0 specification with both Alt Setting 0 (MIDI 1.0 fallback)
and Alt Setting 1 (UMP native) descriptor support.

Driver features:
- UMP (Universal MIDI Packet) read/write with atomic message framing
- Protocol negotiation: Endpoint Discovery, Config Request/Notify,
  Function Block Discovery (embedded in driver)
- Group Terminal Block descriptor via GET_DESCRIPTOR
- Alt Setting switch handler with endpoint re-arm
- Static allocation, no dynamic memory, ISR-safe

Build system:
- Register midi2d_* in usbd.c driver table
- Add TUD_MIDI2_DESCRIPTOR macros to usbd.h
- Add config defaults (CFG_TUD_MIDI2_*) to tusb_option.h
- Add midi2_ump_word_count() to midi.h (shared by Device and Host)
- Add midi2_device.c/h to family.cmake and CMakeLists.txt
- Add midi2_device.h include to tusb.h

All changes guarded by #if CFG_TUD_MIDI2 (default 0). Zero impact on
existing drivers and examples.

Tested: Raspberry Pi Pico (RP2040), Linux ALSA, Windows MIDI Services

1 files changed, 8 insertions, 0 deletions

diff --git a/src/tusb.h b/src/tusb.h
index c80c8433c..aa6b461e5 100644
--- a/src/tusb.h
+++ b/src/tusb.h
@@ -63,6 +63,10 @@
     #include "class/midi/midi_host.h"
   #endif
 
+  #if CFG_TUH_MIDI2
+    #include "class/midi/midi2_host.h"
+  #endif
+
   #if CFG_TUH_VENDOR
     #include "class/vendor/vendor_host.h"
   #endif
@@ -108,6 +112,10 @@
     #include "class/midi/midi_device.h"
   #endif
 
+  #if CFG_TUD_MIDI2
+    #include "class/midi/midi2_device.h"
+  #endif
+
   #if CFG_TUD_VENDOR
     #include "class/vendor/vendor_device.h"
   #endif