Moves gopls/internal/robustio to internal/robustio.
Allows usage by packages in x/tools outside of gopls.
Change-Id: I71743c3a91458b77f12606b743b5de7e23cc5051
Reviewed-on: https://go-review.googlesource.com/c/tools/+/460116
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>
Run-TryBot: Tim King <taking@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
Tim King