mapping of `expand` to `inclusive`

[jjallaire]

Noted that the Prosemirror inclusive attribute is mapped to both here:

https://github.com/alexjg/amg-prosemirror/blob/41156763da2247f6a48ac92db8bc8fdbf566cd8e/src/pmToAm.ts#LL73C19-L73C19

I'm not sure if Prosemirror has an analogous concept to "both" (it may only support "none" and "after"). Here are the PM docs on inclusive: https://prosemirror.net/docs/ref/#model.MarkSpec.inclusive. Note that this seems to imply you'll get "both" behavior only when the text is at the start of the parent node.