[zcash/zcash] Add Sapling support to z_getbalance and z_gettotalbalance (#3436)

bitcartel commented on this pull request.

> «\nArguments:\n»
«1. minconf (numeric, optional, default=1) Only include private and transparent transactions confirmed at least this many times.\n»
«2. includeWatchonly (bool, optional, default=false) Also include balance in watchonly addresses (see ‘importaddress’ and ‘z_importviewingkey’)\n»
«\nResult:\n»
«{\n»
» \»transparent\»: xxxxx, (numeric) the total balance of transparent funds\n»
— » \»private\»: xxxxx, (numeric) the total balance of private funds\n»
+ » \»private\»: xxxxx, (numeric) the total balance of private funds (in both Sprout and Sapling addresses)\n»

Filed https://github.com/zcash/zcash/issues/3486