non-permanent write permissions

[arnauorriols]

• Only counts for signed and tagged packets
• Count per Topic, not overall
• Needs pre_handle() to be called on handle_signed_packet and handle_tagged_packet, and a check on the send version throwing an error

Unix:
1: Related to milestone timestamp for now
2: Trust Author and take Millis since epoch
3: ?

NumBranchMsgs: Counter per branch required, and stored in state in case we switch to lean/lite.

• Can be done by counting total of Cursor in KeyStore

NumPublishedMsgs: Permissions are per branch, so needs a counter per publisher per branch

• Can be done by taking the Cursor value of Identifier in KeyStore

Q:
Do we want NumMilestones?