Add intro to raster analysis in Julia, Python and R

This is the markdown output from quarto from the quarto notebook which is located at https://github.com/felixcremer/lhbarticles/. The file is manually copied and the figures are copied into a subfolder in img and the links are manually replaced to point at the right directory.

This is a work in progress. Especially the python parts are not done yet. I am opening this merge request now to discuss the conversion of the quarto into markdown for mkdocs.

It would be nice to use content tabs for the different languages instead of the linear layout we have for now. But I am not sure, whether we could automatically get the tabbing information from quarto. https://squidfunk.github.io/mkdocs-material/reference/content-tabs/