samd: Support WiFi using external esp32 based modules.

[robert-hh]

Such like the u.blox W102, Adafruit Airlift products or just any ESP32 based hardware. The ESP32-WROOM with at least 2MB flash module is sufficient. The actual firmware support full WiFi with SSL on boards with a SAMD51x19 MCU external flash and basic WiFi without SSL for SAMD51x19 boards with the file system in internal flash. SAMD21x18 boards with external flash could as well provide basic WiFi.
The build was tested using the test script and performs identical to the Arduino Nano 2040 connect, which is not a surprise. The PR includes documentation.
For providing the firmware binaries requires required for the ESP32 modules I have made PR to micropython-lib in the espflash path. It seemed to be the best place for it.
This extension is based on the great work of @iabdalkader with the network_ninaw10 package and his support during the implementation.

This is a re-submit of PR #11219, which was closed since I renamed the branches. There is also a branch based on the esp-hosted firmware, which is similar for WiFi, but performs much better with BLE. See the notes down in PR #11219.

[github-actions]

Code size report:

   bare-arm:    +0 +0.000% 
minimal x86:    +0 +0.000% 
   unix x64:    +0 +0.000% standard
      stm32:    +0 +0.000% PYBV10
     mimxrt:    +0 +0.000% TEENSY40
        rp2:    +0 +0.000% RPI_PICO
       samd:    +0 +0.000% ADAFRUIT_ITSYBITSY_M4_EXPRESS

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.39%. Comparing base (a61c446) to head (0e46cdf).
Report is 11 commits behind head on master.

❗ Current head 0e46cdf differs from pull request most recent head c2e9019

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@@            Coverage Diff             @@
##           master   #12464      +/-   ##
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- Coverage   98.39%   98.39%   -0.01%     
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  Files         161      158       -3     
  Lines       21204    20938     -266     
==========================================
- Hits        20864    20601     -263     
+ Misses        340      337       -3     

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[robert-hh]

@dpgeorge The PR is simplified, in that the additional network.NINAW10 interface is dropped. So only the choice of using the Pin assignments of the board definition files is available. That seems acceptable, since most likely with the SAMD boards the matching NINAW10 boards are used. As a result of that change, there are no changes to the network_ninaw10.c file any more, and the changes to the drivers/nina*.c are mostly for supporting a port-specific variant of the wifi_nina_bsp.c file, like it's done for the esp_hosted driver of the Portenta C33 port.

[robert-hh]

Support for BLE is prepared as well, but since ATM Jimmo is digging up BLE support in #8945, I'll wait a little bit. B.t.w.: Jimmo is working on other round-kick style PRs as well, like #12211 or #12443. Are these to be merged soon? Since they affect almost all ports, keeping WIP PRs in sync is a constant challenge.

[robert-hh]

Rebased & conflicts resolved. @jimmo Is it possible to access the value of BOARD_VARIANT in manifest.py scripts?

[robert-hh]

Added build variants WLAN and WLAN_BLE. The latter supports WiFi and BLE.

There is another variant for WiFi and BLE support available based on the esp_hosted firmware for the ESP32. That one has a slightly better WiFi performance and much better BLE reliability, but the code size is ~70k larger, filling completely up the 512k code space of SAMD51x19 devices. The only devices that could comfortably support it are the Sparkfun SAMD51 and the no-yet-merged Adafruit Grand Central M4 device using the SAMD51x20 MCU with 1 M flash.

The plus side of the NINA solution, that it would even fit on a SAMD21 (useful or not) or SAMD51 w/o external flash, if SSL support is omitted. That's already foreseen in the build script.