Add initial support for USB MSC (#5466)

* Add initial support for USB MSC

* Add Firmware Upload/Download With MSC

Current running firmware is available as file inside the MSC Disk. To update the firmware on the ESP, just copy a regular firmware bin into the drive

* Support overwriting of the firmware file

Overwriting a file is done totally differently on MacOS, Windows and Linux. This change supports it on all of them.

* Allow CDC, FirmwareMSC and DFU to be enabled on boot

* Add example ESP32-S2 USB-ONLY board

* Various device code optimizations

Added `end()` methods to MSC classes
Made begin() methods safe to be called multiple times
Optimized CDC class

* Fix CDC Connect/Disconnect detection in Arduino IDE on Windows

* Rework cdc_write

* Update ESP32-S2 board configs

Author: me-no-dev

Diff for: CMakeLists.txt

@@ -34,6 +34,9 @@ set(CORE_SRCS
   cores/esp32/StreamString.cpp
   cores/esp32/USB.cpp
   cores/esp32/USBCDC.cpp
+  cores/esp32/USBMSC.cpp
+  cores/esp32/FirmwareMSC.cpp
+  cores/esp32/firmware_msc_fat.c
   cores/esp32/wiring_pulse.c
   cores/esp32/wiring_shift.c
   cores/esp32/WMath.cpp
@@ -151,6 +154,7 @@ set(includedirs
   libraries/SPI/src
   libraries/Ticker/src
   libraries/Update/src
+  libraries/USB/src
   libraries/WebServer/src
   libraries/WiFiClientSecure/src
   libraries/WiFi/src