v2-docs: Add docs for inline datasets, grpc, and port legacy docs

[jonmmease]

Adds new docs and examples for how inline datasets work, and on using VegaFusion Server over gRPC.

Also adds a small section on Vega-Lite that directs people to vl-convert.

Also ports over the relevant ABOUT and COMMUNITY sections from the v1 docs.

Also updates the VegaFusion title logo to swap letter color based on dark mode toggle.