Nicla Vision: initial variant support

[bogdanarduino]

Initial support for the Nicla Vision. Tested thus far:

• Compilation and flashing of core;
• Compilation of basic blink and serial print sketches;
• LED pins config;
• USB CDC port able to produce output;
• generated zephyr.dts checked against the hardware config for pins and muxes;
• no detailed peripheral checks done at this point.

[KurtE]

I thought about doing this a while ago, and created an issue: #137
Which later I closed and now reopened

I dropped it at the point, As it was not sure how to setup the GC2145 camera to use the main memory and have enough
memory to make it worthwhile. I built some of the zephyr samples and they did not do much.
They setup memory poll:

ONFIG_VIDEO_BUFFER_POOL_NUM_MAX=2
CONFIG_VIDEO_BUFFER_POOL_SZ_MAX=160000

With this configuration, from the drivers/video/capture sample, There is not enough memory there to
allocate two 320x240x2 buffers, So could only do something like 160x120 images, with the current released code.

I was trying to resolve some of that, by adding a SNAPSHOT mode to the vision code, that would start the camera
for one image each time, and allowed you to configure to only need one buffer instead of two. With my own
test apps, was able to then capture 320x240. But even with that was unsure if it could be setup in the Arduino LLText
setup.

I have a Pull rquest to Zephyr to add that mode, so far waiting on reviews.
zephyrproject-rtos/zephyr#98004

So will be interesting to see how well your boards setup will work. Keeping fingers crossed.