* 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

workaround for #5043. There is a timing issue with HardwareSerial::end. I'm not sure what is hung, but it should be possible to see this in jtag, as it does cause a reboot if you let it. The delay needs to be before you detach the device!?

Fixes: https://github.com/espressif/arduino-esp32/issues/5005

This is very much still work in progress and much more will change before the final 2.0.0

Some APIs have changed. New libraries have been added. LittleFS included.
Co-authored-by: NSeon Rozenblum <seonr@3sprockets.com>
Co-authored-by: NMe No Dev <me-no-dev@users.noreply.github.com>
Co-authored-by: Ngeeksville <kevinh@geeksville.com>
Co-authored-by: NMike Dunston <m_dunston@comcast.net>
Co-authored-by: NUnexpected Maker <seon@unexpectedmaker.com>
Co-authored-by: NSeon Rozenblum <seonr@3sprockets.com>
Co-authored-by: NmicroDev <70126934+microDev1@users.noreply.github.com>
Co-authored-by: Ntobozo <tobozo@users.noreply.github.com>
Co-authored-by: Nbobobo1618 <bobobo1618@users.noreply.github.com>
Co-authored-by: Nlorol <lorolouis@gmail.com>
Co-authored-by: Ngeeksville <kevinh@geeksville.com>
Co-authored-by: NLimor "Ladyada" Fried <limor@ladyada.net>
Co-authored-by: NSweety <switi.mhaiske@espressif.com>
Co-authored-by: NLoick MAHIEUX <loick111@gmail.com>
Co-authored-by: NLarry Bernstone <lbernstone@gmail.com>
Co-authored-by: NValerii Koval <valeros@users.noreply.github.com>
Co-authored-by: N快乐的我531 <2302004040@qq.com>
Co-authored-by: Nchegewara <imperiaonline4@gmail.com>
Co-authored-by: NClemens Kirchgatterer <clemens@1541.org>
Co-authored-by: NAron Rubin <aronrubin@gmail.com>
Co-authored-by: NPete Lewis <601236+lewispg228@users.noreply.github.com>

This reverts commit 4b3f5c8e.

* Fixes UART detach.  Fixes #3878

* 0 is not a good holder value for pins!

* 0 is not a good holder value for pins!

* API compatibility to AVR, ESP8266, et al

* Add non-blocking HardwareSerial::read(buffer, size) extension (ESP8266 portability)

* Refactor for fewer indirect calls.

* add option to Flush() to only clear txQueue

Add the option to cause Flush() to just wait for tx data to clear the tx fifo and uart, leave the rx queue and rx fifo as is.

* support tx only flush()

* support tx only Flush()

* support txOnly for Flush()

* compatibility to Stream()

* compatibility for Stream()

* default value error

* default value error

* Update esp32-hal-uart.h

* Update esp32-hal-uart.c

* Update HardwareSerial.cpp

* sp

* correctly implement flushTxOnly()

* Expose uartStartDetectBaudrate(uart_t *) in esp32-hal-uart.h and call it from HardwareSerial::begin() if baudrate detection is requested (by passing a baudrate of 0) to solve baudrate detection problems

* Avoid a division by zero error in uartGetBaudRate()

* Add updateBaudRate to hardware serial

* remove flush

* Fix tab

* Added baudrate detection to esp32-hal-uart and HardwareSerial

* Solved compiler warning for uartResizeRxBuffer()

* Add unit to header variable name (timeout_ms)

* Reverting accidentally changed files to master

* Add small delay after baudrate detection

* TX Flow Control and Code cleanup

* Use semaphore instead of delay

TX functionality is done.

* Use single buffer and empty queue on exit

* Fix compile issues because of LwIP code relocation

* Add temporary header to fix Azure not compiling

* Fix AsyncUDP early init

* AsyncUDP Multicast fixes

* Add source mac address and rework multicast

* Allow redefinition of default pins for Serials 1 and 2

* Update IDF to 3276a13

* Update esptool.py to 2.5.0

* Fix sketches

* Fix log level in BluetoothSetial

Add functionality allowing rxBuffer of HardwareSerial to be changed in size via HardwareSerial::setRxBufferSize. (#1855)

If you develop on windows and need cr/lf files, see this:

    https://git-scm.com/book/en/v2/Customizing-Git-Git-Configuration#_formatting_and_whitespace

    Git can handle this by auto-converting CRLF line endings into LF
    when you add a file to the index, and vice versa when it checks out
    code onto your filesystem. You can turn on this functionality with
    the core.autocrlf setting. If you're on a Windows machine, set it
    to true - this converts LF endings into CRLF when you check out code:

    $ git config --global core.autocrlf true

* HardwareSerial - availableForWrite() support

* fix indentation errors (tab vs space)

Added argument to HardwareSerial.begin to specify whether the logic levels of the UART rx and tx lines should be inverted (#719)

* Print error when serial number is invalid

* Move to the first check, change end by return

usefull for ESP8266 compatibility

Fixes: https://github.com/espressif/arduino-esp32/issues/270

NOTE: UART1's default pins can be used only when SPI Flash is DIO

thanks @Ladyada

many possible problems fixed in preparation for thread-safe