refactor: replace pkg/errors with %w

[hbagdi]

What this PR does / why we need it:

Removes the use of github.com/pkg/errors package and instead uses error checking additions shipped in Go 1.13.

Special notes for your reviewer:

This is based on top of #748. Review the HEAD of the PR. I'll rebase once 748 is merged in.

[rainest]

For anything we have outstanding, is there a quick grep we can run to try and catch any new errors that still use the old format?

[hbagdi]

For anything we have outstanding, is there a quick grep we can run to try and catch any new errors that still use the old format?

There should not be any because the package was removed in go.mod, meaning we are not using the package in our codebase anywhere.