Replace FrozenSequence with IsFrozen boolean in Solomachine Client

[AdityaSripal]

Unnecessary to have frozen sequence since we don't allow anything to verify before frozen sequence anyway.

[colin-axner]

What is going to be returned for the FrozenHeight? 1?

[colin-axner]

From 02-client Update

     // prevent update if the client is frozen before or at header height
    if clientState.IsFrozen() && clientState.GetFrozenHeight().LTE(header.GetHeight()) {
        return sdkerrors.Wrapf(types.ErrClientFrozen, "cannot update client with ID %s", clientID)
    }