Implement sapling viewing keys | 2.0.8

[MarcelusCH]

As our discussion on Discord, we go now forward with sapling viewing keys .

References:

• Implement Sapling viewing keys zcash/zcash#3060
• Add support for importing and exporting sapling ivk #3060 zcash/zcash#3822

I think that this are the needed dependencies for doing it (by this initial PR).
The different updates have been committed with same PR name as zcash core node.

I will commit the bellow updates as well into the BtcZ node v2.0.8-rc1 (or should this may be a beta?):

• https://github.com/zcash/zcash/pull/4362/commits
• https://github.com/zcash/zcash/pull/4370/commits

Change log up to this PR open

add z_gettreestate RPC
Fix the use of 0 as expiryheight in createrawtransaction, to disable expiry
Bitcoin 0.12 wallet PRs 1
Fix CVE-2017-18350
Wallet interface refactor
Update z_viewtransaction
insightexplorer: LOCK(cs_main) during rpcs
Return address and type of imported key in z_importkey

[MarcelusCH]

Ok, there are some more update to pull in before to be able to merge successfully the import/export/init usage of full viewing key.
Here is the backward compatibility list of what we need some of (not all).
https://github.com/zcash/zcash/pulls?page=38&q=is%3Apr+is%3Aclosed
But I stuck one witch one is depending each other.
(We not schould add every update)

[MarcelusCH]

Added also the followings update in the last commit :

• Upstream PRs relating to strMiscWarning
• Replace tuples by classes in asyncoperation_sendmany

This commit allows now the binaries to be compiled (on ubuntu 20.04) and to use the z_importviewingkey, z_exportviewingkey, and also to able to see the shilded tx with only the viewing key (instead the std spending key) with the z_viewtransaction function.

[MarcelusCH]

Updated deprecation to blk 1208650 (AUG 2023) and renamed as stable version.

[cryptorex]

this was merged in #70