Problem

Currently, checksum validation is implemented only for TokenId introduced in PR #380. This issue aims to extend checksum support to other entity types — FileId, AccountId, ContractId, TopicId, and ScheduleId for consistency across with the other Hiero SDKs like Java and Javascript.

Solution

• Add checksum field and validate_checksum(), and to_string_with_checksum() methods to each corresponding class.
• Write unit tests for each entity type (valid, invalid, and mismatched checksums)

Alternatives

No response