refactor: replace midi2_host (Waveshare) with midi2_host_feather

Remove the Waveshare RP2350-USB-A host example and board definition.
The Feather RP2040 USB Host is the TinyUSB reference board for
PIO-USB host and does not require the CFG_TUSB_DEBUG workaround
needed by the Waveshare (R13 pull-up issue).

One host example is sufficient for the PR. The Feather variant has
an improved display with splash, spinner, and 6-line live view.

Author: sauloverissimo

examples/host/CMakeLists.txt

@@ -13,7 +13,7 @@ set(EXAMPLE_LIST
   device_info
   hid_controller
   midi_rx
-  midi2_host
+  midi2_host_feather
   msc_file_explorer
   )