validate orchard flags in v5

[oxarbitrage]

Motivation

We need to make sure at least one flag is set in transactions version 5 when the number of actions is at least one. Attempts to close #2433

Specifications

[NU5 onward] If effectiveVersion >= 5 and nActionsOrchard > 0, then at least one of enableSpendsOrchard and enableOutputsOrchard MUST be 1.

https://zips.z.cash/protocol/protocol.pdf#txnconsensus

Solution

Create a new has_enough_orchard_flags() method and call it from the transaction verification. Performance wise i think there is maybe some overlap between this new method and has_inputs_and_outputs() but i hope that is minimal.

Review

Anyone cvan review but will be good if @teor2345 can take a look.

Reviewer Checklist

• Code implements Specs and Designs
• Tests for Expected Behaviour
• Tests for Errors

[teor2345]

Looks good!