vscgo: retract the vscgo "module"

[Hyang-Ah Hana Kim]

https://pkg.go.dev/github.com/golang/vscode-go/vscgo

Follow the instruction in golang/go#67567 (comment)

Option 1)

1. Add back the go.mod file in github.com/golang/vscode-go/vscgo
2. Add a retract directive to the go.mod. Tag v0.0.1-deprecated and make sure it's seen by proxy.golang.org.
3. Remove go.mod file.

Option 2)

1. Create a branch
2. Commit a change that bring back go.mod with retract.
3. Tag the branch with vscgo/v0.0.1-deprecated, and forget about the branch.

If the option 2 works, I think it is better (not leaving the trace in the main branch)

cc @suzmue

[GopherBot]

Change https://go.dev/cl/591158 mentions this issue: vscgo: retract the vscgo module

[GopherBot]

Change https://go.dev/cl/591159 mentions this issue: Revert "vscgo: retract the vscgo module"