cmd/go: missing checksums for dependencies of go get arguments and tests of external dependencies [1.20 backport] #60001
Description
@bcmills requested issue #56222 to be considered for backport to the next 1.20 minor release.
@gopherbot, please backport to Go 1.19 and 1.20. We should at least report a clear error for missing checksums instead of trying to build with the wrong language version.