Investigate and clean the validate_basic method

[Shivani912]

The method validate_basic appears in almost all domain type definitions, e.g., Counterparty, ConnectionEnd, MsgConnectionOpenConfirm, etc. In most of the implementations, this method returns an Ok() result. It's unclear if we should keep it around.

Investigate:

• What was the original intended purpose of validate_basic?
• Can we remove it altogether, or do some types still need it? Intuitively, conversion from the Raw type into the domain type (see below an example) handles all validation. Domain types are a rather new features, and perhaps they make the method validate_basic unnecessary.

https://github.com/informalsystems/ibc-rs/blob/2b5029b50e1cfd4181e2dfcf8d1b76c7b9d833e6/modules/src/ics03_connection/msgs/conn_open_init.rs#L84-L99