This change refactors code actions to handle the Context.Only parameter,
which indicates which code actions a language server should execute.
Change-Id: Iddfccbbeba3a53fde2aa8df844434f2ab9d01666
Reviewed-on: https://go-review.googlesource.com/c/tools/+/184158
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>