Update support for handling go packages by handling missing go
dependencies. Make use of go modules and the go proxy (see
https://tip.golang.org/cmd/go/#hdr-Module_proxy_protocol for more
details on the proxy implementation) to discover what artifacts are
needed.
A new go-dep build_pattern that will package all versions that the
go-proxy finds is also added as part of this change. Additional rework
of the golang build_pattern (and Makefile build_pattern as a number of
go packages use Makefiles) to use module vendoring when module
configuration is detected was added as well.
The new functionality is also intended to be used by a higher level
tool that will wrap autospec calls to build missing dependencies as
well as the requested package.
William Douglas