Previously, the commit SHAs and PR numbers referenced in the generated
`CHANGELOG.md` were not automatically converted to links in the GitHub
UI (as happens for release notes and issue/PR comments). This made it
less straight-forward for someone reading the changelog to get to the
commit/PR corresponding to a change.
This commit updates the tooling that generates the changelog to convert
the commit SHA and the corresponding PR number (referenced at the end of
the commit message header) to links.
PR Close#42732
Move the release notes tooling under its own directory under release rather than
within publish, in preparation to have a release note generation command for ad-hoc
release note generation.
PR Close#42225
George Kalpakas
Joey Perrott