builtin: deprecate errwrap.Wrapf() throughout

[alrs]

github.com/hashicorp/errwrap has deprecated Wrapf(), and recommends using fmt.Errorf().

fmt.Errorf() added support for error wrapping in go1.13. Vault has a hard requirement of go1.16.2, so this isn't an issue.

This PR deprecates errwrap.Wrapf throughout github.com/hashicorp/vault/builtin and all of its subpackages. I organized the PR as one-commit-per-package to aid anyone who should ever need to do a git bisect, but I'm just as happy to squash this into a single commit.

[ncabatoff]

Hey @alrs,

This is great, thanks! I'm going to have to do some investigation / due diligence to reassure myself that this won't break anything, but I hope to merge this soon.

[alrs]

I'm going to have to do some investigation / due diligence to reassure myself that this won't break anything

Makes sense to me, thanks for taking a look at this instead of letting it sink to the bottom of the tank. :).

[ncabatoff]

I didn't find a good example of a changed line in this PR that was being consumed by other code which was testing for an embedded error. So to reassure myself I modified reloadutil.Reload to use fmt.Errorf, and checked that TestReload_KeyWithPassphrase still worked. Since all the "query" errwrap func are built on errwrap.Walk, I don't feel the need to check each of them. And of course there were already tests in hashicorp/errwrap#9, I just wanted to be doubly sure.