Use More Dynamic Gene Loading

[ilan-gold]

I made a few small fixes and also updated examples where possible to be a bit more efficient with the dynamic gene loading.

• Add intermediate path creation because pandas does not by default
• Make the combat data sparse csc which vitessce can load quickly
• Upgrade anndata
• Use dense visium X matrix chunked efficiently with filtered heatmap (instead of filtered dense matrix loaded all at once)
• Use sparse matrices for kuppe as in combat
• Same for marshall and meta-azimuth