Update types in Account transactions

[rwalworth]

Part of merging #252 involved updating types to work for testing all SDK languages, notably using string instead of int64 types. We should go back and update these for the Account transaction tests we have, as well as adding proper bound tests if they are not already implemented. This will involve changing the types in the SDK servers as well.

• TCK-Java: Update Account endpoint types
• TCK-JS: Update Account endpoint types
• TCK-Go: Update Account endpoint types
• TCK-C++: Update Account endpoint types
• TCK-Swift: Update Account endpoint types
• TCK-Rust: Update Account endpoint types
• TCK: Update Account endpoint types