Add uint64_t or int64_t support for SafeString.print

[dakotahorstman]

It'd be very convenient if SafeString objects could support printing uint64_t and int64_t types. For my use case, I'm converting these types to hexadecimal (e.g. SafeString.print(num, HEX) like Serial.print(num, HEX)).

This is already supported by BufferedOutput, for example, as the Print object implements functionality that could likely be replicated over.

I understand this deviates from wstring as String doesn't support these types either, but it'd still be great to have.

[drmpf]

Happy to consider a pull request to implement this.

[dakotahorstman]

Sure, I can look into creating a PR. I assume to test, I would need to upload those outlined in examples/SafeString_Tests to an Arduino and just see if it works? Any specific board(s) I should use/you want me to test with specifically?

I have the following:

• Adafruit STM32F405 (and my own STM32F405 variant)
• Arduino Nano 33 IoT
• Uno 3
• Mega 2560
• Silicognition wESP32

[drmpf]

testing on a 16bit and 32bit board should be enough