Support vendored major upgrades for Go

[hugoboos]

What would you like Renovate to be able to do?

Update major versions in projects that have Go vendoring enabled.

Eg. github.com/google/go-github/v48 to github.com/google/go-github/v50

Reproduction repository: https://gitlab.com/hugoboos/renovate-go-update-import

Related discussion: #20996

If you have any ideas on how this should be implemented, please tell us here.

At the moment Renovate updates go.mod. This should be done by the mod tool. This tool is already being used by Renovate. Only the order should be changed.

1. Run mod to change the import paths
2. Run go mod tidy, this will update go.mod. Possible that version is different from that Renovate selected.
3. Change the version in go.mod for the updated package.
4. Run go mod tidy
5. Run go mod vendor
6. Commit

Is this a feature you are interested in implementing yourself?

No

[rarkins]

Reproduction imported to https://github.com/renovate-reproductions/21010 (note: in future it would be appreciated if you can reproduction github.com to make it more easily forkable)

[rarkins]

This one will need someone to do some experimentation. Renovate usually:

• Updates a package file (e.g. go.mod) manually, then
• Runs one or more commands to update "artifacts" (go.sum, vendored files, etc)

In this case it's being asked to skip the go.mod update and go directly to running commands. We may not be able to easily skip the update but we may be able to reverse it prior to running commands.

[hugoboos]

If I can help to test something, let me know.