This allows IsSorted() and IsConsistent() to be used by themselves.
IsSorted() with a precomputed set is used so that we don't create this
set multiple times.
Many edge cases exist when parents in a child-with-parents package can
spend each other. However, this pattern should also be uncommon in
normal use cases.
While allowing submitted packages to be slightly larger than what
may be allowed in the mempool to allow simpler reasoning
about contextual-less checks vs chain limits.
Duplicates of normal transactions would be found by looking for
conflicting inputs, but this doesn't catch identical empty transactions.
These wouldn't be valid but exiting early is good and AcceptPackage's
result sanity checks assume non-duplicate transactions.
