[Feature-request]: Merkle trie properties

### Describe the desired feature or improvement

1. How challenging would it be to create a generic set of merkle trie properties?
2. Do merkle trie library interfaces have enough commonalities for this kind of test suite to be possible?

No files or tests are named. Start by surveying existing Merkle trie interfaces and the repository's property-testing conventions; define which common properties and interfaces are in scope. Done means the feasibility question is answered with an agreed scope for a generic test suite.

Written by the indexing model from the issue text.