Investigate dynamic choices to export image support to ask directly Excalidraw

[bric3]

Currently supporting a new file for export is added manually.

E.g. there's a file that lists the supported types, however it doesn't seem to be publicly exposed.

From this code

https://github.com/excalidraw/excalidraw/blob/65047cc2cb59843a4305f9088d886edd9b933585/packages/utils/export.ts#L136-L153

1. scene embedding only works on SVG and PNG
2. supported type is driven by the browser support (canvas.toBlob)

So maybe there's a way to query the browser for supported types.

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Note that recognizing a file as having an embedded scene is out of scope there as currently embedded scene is only supported on PNG and already implemented, for other file types it's not yet supported.