Add support for Sapling Extended Full Viewing Keys

[dorianvp]

No description provided.

[Oscar-Pepper]

i believe this is the wrong approach. zingolib already supports sapling extended full viewing keys as they can converted to diversable FVK via the from implemention. UFVKs can be constructed with only the sapling diversable FVKs (orchard and transparent are optional). consumers of zingolib should convert their key material to UFVKs and create the LightWallet with those

[zancas]

Hi @dorianvp what do you think?

[Oscar-Pepper]

i didnt realise this was to serve a zingo-cli feature request. I suppose it doesnt hurt to also accept sapling FVKs as an additional feature rather than adding this logic to zingo-cli and it essentially being duplicated for other consumers

[zancas]

@Oscar-Pepper or @dorianvp can we update this feature with latest dev?

Is this PR review-ready?

[dorianvp]

No, it's far from ready. It only contains the initial structs to support that feature.

[zancas]

Do we still intend to implement this feature?

[dorianvp]

I think we should tag it as low priority.