miniTFTWing examples don't work on RP2040 feathers

[shen-tian]

• Arduino board: Feather RP2040

• Arduino IDE version (found in Arduino -> About Arduino menu): 1.8.19

• List the steps to reproduce the problem below (if possible attach a sketch or
  copy the sketch code in too):

  • Select Feather RP2040
  • Load either of the miniTFTWing examples
  • Build and upload

Underlying issues:

• Example is missing pin assignment code for RP2040 (e.g. Wire.setSDA...).
• RP2040 Feathers use GPIO2/3 for I2C pins. These are valid hardware pins, but are assignable only to Wire1. The mini TFT wing lib (which lives in the SeeSaw lib) only uses Wire.
• The plain Feather RP2040 uses GPIO7/8 for feather pins 5/6. It looks like subsequent boards use GPIO5/6 pins. Don't think this one is fixable in code, but a good comment would have been helpful.