Add MagTag generic display, update ILI0373 display

[brentru]

• Changed the mode in epdConfig from "mono" to "grayscale4" for the 2.9" ILI0373 E-Ink display.
• Added a new definition file components/display/eink-magtag/definition.json for the Adafruit MagTag 2.9" E-Ink display
  • @lorennorman This definition file uses unspecified as defaults for the driver and mode configuration since the firmware should automatically detect the generic definition, perform detection for the display driver, and fill in the PB fields with the appropriate configuration. This felt like the simplest way to achieve this, I am open to other ideas, though.

[brentru]

@lorennorman Seems like the Validate action is failing due to a network issue?

[lorennorman]

This is great, @brentru.

Re: the Action failing, yes it appears imagemagic.org is down right now. Very major library so I'm inclined to Do Nothing now, and if it's still not fixed when we're ready to merge we can manually approve your new image.

Re: using unspecified for mode and driver: OK this is an interesting approach, I like it! I have to make changes to my code to allow those through but it's not much.

mode appears on the web form, should it:

• still appear, but have an "Unspecified" option?
• not appear at all for component types with no mode set in the json?

[lorennorman]

Ooops I just re-read the json and see you added "unspecified" as the mode, that's good.

I will simply add an "Unspecified" option to the EPD mode input.