use lvgl imageconverter unmodified?

[Habbie]

The .c files in src/uicomponents/imgs/ are generated with the online converter (see readme in that dir) and then we modify them. I just reduced the level of modification in a commit in #60, but the difference is still big. Part of it is clang-format. It would be nice if we can use the converter without any manual postprocessing (in which case we'd exclude the files from clang-format perhaps)

[Habbie]

In #73 we found

• LVGL can load PNGs from disk or a memory buffer fine
• the built in PNG decoder appears to be slow
• but there's caching
• this caching costs RAM
• the icons as we use them now in imgs/ are fully rendered and cost flash and not RAM

so switching to the decoder fully may not make sense right now, especially if we want to target ESP32 later. However, the possibility to decode at runtime might be great for theming later.