Implement TokenDatabaseReadableKVState

[IvanKavaldzhiev]

Problem

We should add implementation for TokenDatabaseReadableKVState, so that we can return tokens in PBJ format from DB.

Solution

Add TokenDatabaseReadableKVState in the following manner:

• Copy TokenDatabaseAccessor logic as a starting point
• Add repository logic for reading tokens from DB
• Add a new converter between entity and token DTO types to PBJ, so that the returned object is compliant with the hedera.app state

Alternatives

No response