Schematics, symbols, boards and footprints all get the ability to store
files inside their file structures. File lookups now have a
kicad-embed:// URI to allow various parts of KiCad to refer to files
stored in this manner.
kicad-embed://datasheet.pdf references the file named "datasheet.pdf"
embedded in the document. Embeds are allowed in schematics, boards,
symbols and footprints. Currently supported embeddings are Datasheets,
3D Models and drawingsheets
Fixes https://gitlab.com/kicad/code/kicad/-/issues/6918
Fixes https://gitlab.com/kicad/code/kicad/-/issues/2376
Fixes https://gitlab.com/kicad/code/kicad/-/issues/17827
