cmd/go: upgrade go install pkg@version's go using local mod, work
This CL changes the toolchain selection behavior for go install pkg@v
and go run pkg@v to also take into account the go and toolchain version
lines in the containing go.mod and go.work file.
Before this change, the go command would detect that go install
pkg@version or go run pkg@version was being run and skip the standard
behavior that would select the toolchain based on the go version in the
go.mod or go.work file. It would instead check the go line of the module
being downloaded and switch to that version if necessary.
With this change, the go command does not skip the standard behavior. It
proceeds to determine if an upgrade is required based on the containing
go.mod or go.work file's go and toolchain lines. Then, it checks the
module being installed to see if it would require a higher version than
the determined upgrade (or the local version if no upgrade was
determined). If it does require a higher version, then a switch happens
to that version, and if not the upgrade logic proceeds as usual doing
the upgrade if one was determined.