cmd/go/internal/modfetch/codehost: add Unwrap to custom error types

[psampaz]

Updates #30322

This change adds the Unwrap method to RunError and VCSError. These 2 error types are the only custom error type of the codehost that has a nested exported error.

[gopherbot]

This PR (HEAD: 22b7108) has been imported to Gerrit for code review.

Please visit https://go-review.googlesource.com/c/go/+/194599 to see it.

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[gopherbot]

Message from Bryan C. Mills:

Patch Set 1: Code-Review-1

These types are in internal packages. There is no reason to update them as of yet.

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[gopherbot]

Message from Pantelis Sampaziotis:

Patch Set 1:

Patch Set 1: Code-Review-1

These types are in internal packages. There is no reason to update them as of yet.

ok, should I close it then?

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[gopherbot]

Message from Bryan C. Mills:

Patch Set 1:

Patch Set 1:

Patch Set 1: Code-Review-1

These types are in internal packages. There is no reason to update them as of yet.

ok, should I close it then?

Yes, let's do that.

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Please don’t reply on this GitHub thread. Visit golang.org/cl/194599.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

This PR is being closed because golang.org/cl/194599 has been abandoned.

Error types are internal to cmd/go — no update is needed as of yet.