[ICS02] [ICS03] Missing ClientType, ClientId validation checks

[Farhad-Shabani]

Summary

Part of #233

• Some IBC messages take in client_state as Any and the correctness of their included ClientType is not checked.
  E.g. client creation handler is missing that.

• Given that the ClientType is a part of the client identifier constructor, some ClientId checks are missing too.

• Similar check in IBC-go is carried out by ValidateClientType

[plafer]

This is called in MsgCreateClient::ValidateBasic(), so IIUC this issue is a subset of (and therefore a duplicate of) #233

[Farhad-Shabani]

This is called in MsgCreateClient::ValidateBasic(), so IIUC this issue is a subset of (and therefore a duplicate of) #233

Regarding #233, we ideally should go through a list of necessary checks and add any missed validation steps by calling/importing relevant ready-to-go functions or error variants. As for the ClientType, There isn't such a callable method. So, even though this issue is implicitly part of that, I wanted first to get on the same page about what a valid ClientType string looks like. Plus, breaking down the changes into smaller, more specific chunks, so we could keep things clearer for the review.