Go 1.17 has a new treatment of go.mod where it tracks more indirect
dependencies in return for needing to fetch and load fewer transitive
go.mod files.

This commit opts in to that new treatment and adds all of the additional
indirect dependencies which contain packages that Terraform directly or
indirectly makes use of.

There are more details on what's going on here in the "Lazy Module Loading"
design document:
    http://golang.org/design/36460-lazy-module-loading

(the design document was written assuming this would land in Go 1.15, but
it actually landed in Go 1.17 and so it's "go 1.17" that selects the new
behavior in spite of the examples in that document.)