We now have a full roster of privacy policies. We can graph the
relationships between the policies; arrows point from more-private to
less-private, and each policy is permitted to reveal information covered
by all policies pointing to it (in addition to the extra information it
is permitted to reveal).
FullPrivacy
v
AllowRevealedAmounts
v v
AllowRevealedRecipients ---- AllowRevealedSenders
v / v
AllowFullyTransparent <- AllowLinkingAccountAddresses
v v
NoPrivacy
The synthetic `LegacyCompat` policy now uses the `AllowFullyTransparent`
policy for backwards compatibility, and the `FullPrivacy` policy if the
sender or recipients involve Unified Addresses.
Closeszcash/zcash#5677.
Closeszcash/zcash#5678.