fix(hmac): add missing www-authenticate headers

[nowNick]

Summary

When kong returns 401 Unauthorized response it should return WWW-Authenticate header with proper challenge. HMAC auth was missing this header.

Related PRs:

• fix(jwt): add missing www-authenticate headers #11792
• fix(key-auth): add missing www-authenticate headers #11794
• fix(basic-auth): add missing www-authenticate headers #11795
• fix(ldap): add missing www-authenticate headers #11820
• fix(oauth2): add missing www-authenticate headers #11833

RFCs & Materials

• https://httpwg.org/specs/rfc7235.html#status.401
• https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/WWW-Authenticate

Checklist

• The Pull Request has tests
• A changelog file has been created under changelog/unreleased/kong or skip-changelog label added on PR if changelog is unnecessary. README.md
• N/A There is a user-facing docs PR against https://github.com/Kong/docs.konghq.com - PUT DOCS PR HERE

Full changelog

• add WWW-Authenticate header to hmac 401 response

Issue reference

• Fix WWW-Authenticate header not present when Kong and plugins return HTTP status 401 #7772
• KAG-321

[team-gateway-bot]

Cherry-pick failed for master, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally.

git remote add upstream https://github.com/kong/kong-ee
git fetch upstream master
git worktree add -d .worktree/cherry-pick-11791-to-master-to-upstream upstream/master
cd .worktree/cherry-pick-11791-to-master-to-upstream
git checkout -b cherry-pick-11791-to-master-to-upstream
ancref=$(git merge-base 75850071308b6a96e15c6c1ac4e9090c3cb6e4e4 9f851815190654cb49c530b3f6929fa09d827525)
git cherry-pick -x $ancref..9f851815190654cb49c530b3f6929fa09d827525

[AndyZhang0707]

@nowNick please help and manually cherry-pick to ee, thanks.