Add EIP7736 support

[weiihann]

Primary changes:

• Add new StateEpoch type
• Modify Get, Insert and Delete to include StateEpoch. If trying to access expired leaf node, returns error.
• Additional lastEpoch field in LeafNode, included in serialization and node commitment calculation
• Add new ExpiryLeafNode struct

[weiihann]

Here's a general explanation of how expiry works with stateless proofs:

There are 4 scenarios for a given stem:

1. Both prestate and poststate not expired

   • Works as normal

2. Both prestate and poststate expired

   • Works as normal, there shouldn't be any state diffs because they are expired

3. Prestate not expired, poststate expired

   • Works as normal, this indicates that there are no state updates from prestate to poststate, so state diffs do not exist

4. Prestate expired, poststate not expired

   • This indicates that a resurrection has occurred. How to verify:
   • We added a new extension status type called extStatusExpired to indicate if a given stem has expired.
   • If an extension status of a stem is extStatusExpired and any of the postvalue in the stem given in the proof is not absent, then we know that there's a resurrection.