rpc: Remove BindOpt
rpc: Remove BindOpt

Follow up to: https://vanadium-review.googlesource.com/#/c/9136/

Change-Id: Ie3a5b817ec53cd66b369a104bc3b9edc37278d64

vanadium/go.v23,vanadium/go.v23,vanadium/go.v23