Create a minimal python port of the node.js module `lv_img_conv`. Only
the currently in use color formats `CF_INDEXED_1_BIT` and
`CF_TRUE_COLOR_ALPHA` are implemented.
Output only as binary with format `ARGB8565_RBSWAP`.
This is enough to create the `resources-1.13.0.zip`.
Python3 implements "propper" "banker's rounding" by rounding to the nearest
even number. Javascript rounds to the nearest integer.
To have the same output as the original JavaScript implementation add a custom
rounding function, which does "school" rounding (to the nearest integer)
Update CMake file in `resources` folder to call `lv_img_conf.py` instead of
node module.
For docker-files install `python3-pil` package for `lv_img_conv.py` script.
And remove the `lv_img_conv` node installation.
---
gen_img: special handling for python lv_img_conv script
Not needed on Linux systems, as the shebang of the python script is read
and used. But just to be sure use the python interpreter found by CMake.
Also helps if tried to run on Windows host.
---
doc: buildAndProgram: remove node script lv_img_conv mention
Remove node script `lv_img_conv` mention and replace it for
runtime-depency `python3-pil` of python script `lv_img_conv.py`.
Return the build status as return code from the `main` helper function.
In the process convert the handling if the file was sourced or directly
executed into an explicit if/else statement to make the intent clearer.
In case of an build error the error is now reported at the build step,
where the error happened.
Fixes: https://github.com/InfiniTimeOrg/InfiniTime/issues/1292
