Work on kerchunk basics foundation notebook

[norlandrhagen]

• [x] Added content to foundations/kerchunk_basics
• [x] Restructured directory
• [x] Added content for GRIB2 example
• [x] Added content for NetCDF example

To Do:

• [x] Add section of future additions/ideas
• [x] Add Foundations notebook on multi file kerchunk

[github-actions[bot]]

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[norlandrhagen]

Progress on kerchunk_cookbook branch. Merging into main.