[FIXED] PSA: Do not build CRSFforArduino for Arduino Zero and Arduino MKR boards

[ZZ-Cat]

Update 2023-10-22

#44 is merged into the Main-Trunk, and you can now compile every supported target with impunity - Including Arduino Zero and any Arduino MKR board.

This also means that I can get back to working on stuff that really matters, like adding in full telemetry support... starting with #17 and #16.
I have put them off for long enough.

Update 2023-10-19

This will be fixed when #44 is merged into the Main-Trunk.
If you would like to help me test the Pull Request, you can check out the development branch here, flash one of the example firmwares (EG RC Channels or GPS Telemetry) onto any of the development boards in the list below, and provide me with feedback in #44.

Fortunately, I have an Arduino Zero available on hand (to test), and the new code in a2b40a6 works flawlessly on it.
I may elect to leave the Pull Request up for a couple of days. If there isn't any responses by Sun's Day (IE 0900 Hrs, 2023-10-22 NZDT), I will merge the Pull Request into the Main-Trunk under the assumption that all is well.

Remember: Feedback from you guys is very important to me. I can only do so much by going through my own code with a fine tooth comb, before it becomes too time consuming for me (IE taking time away from working on things that really matter to CRSF for Arduino, such as adding new hardware targets, plus adding new features to the firmware itself).

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While I was working on #39, I conducted a compile test across all supported platforms to see if the whole lot would succeed.
In my test, I have found the following boards had failed to compile:

• Arduino MKR Fox 1200
• Arduino MKR GSM 1400
• Arduino MKR NB 1500
• Arduino MKR Vidor 4000
• Arduino MKR WAN 1300
• Arduino MKR WAN 1310
• Arduino MKR WiFi 1010
• Arduino MKR Zero
• Arduino Zero (both USB ports)

As you can see, this bug affects the entire Arduino MKR series of development boards and the Arduino Zero.
If you attempt to compile CRSF for Arduino for any of the boards on the list above, you will be met with convoluted compiler errors and the compilation task will fail. You will not be able to flash CRSF for Arduino onto your target development board!
This is a regression bug that has survived every pre-release of CRSF for Arduino and it can be traced as far back as Version 0.1.0 (basically, when I first started this project) up to the latest pre-release.

This bug is being tracked at #42 and the fix will be available in the upcoming Version 0.5.0 pre-release.

This bug affects CRSF for Arduino's compatibility with the aforementioned development boards on a fundamental level, and it will take some time before this bug is fixed.
As per #25, I was supposed to be on hiatus. However, I am too much of a work-a-holic to stay away from CRSF for Arduino for any length of time. Since I have discovered this bug, I am ending my hiatus and making this bug my top priority.

Until this is resolved, if you need to use CRSF for Arduino on a development board with a similar form factor to any of the MKR series, consider using one of Adafruit's Feather M0 or Feather M4 development boards.

If you need something with the same form factor as the Arduino Zero, consider using one of Adafruit's Metro M0 or Metro M4 development boards.

Every other board in CRSF for Arduino's Compatibility Table is unaffected by this bug, as it is isolated to the Arduino Zero and the entire Arduino MKR series of development boards.