chore: add git-cliff configs for generating changelogs and release notes

[SanchithHegde]

Type of Change

• Bugfix
• New feature
• Enhancement
• Refactoring
• Dependency updates
• Documentation
• CI/CD

Description

This PR adds configuration files for git-cliff for generating changelogs and release notes. In addition, this PR increases the heading levels for each heading in CHANGELOG.md file to align with the changelogs generated by git-cliff.

To update the CHANGELOG.md file with the unreleased commits, you can run:

git-cliff --config .github/git-cliff-changelog.toml --unreleased --prepend CHANGELOG.md

To generate release notes for a GitHub release with contributor mentions (you'll also need another tool (disclaimer: I built this) to substitute committer emails with their GitHub usernames):

git-cliff --config .github/git-cliff-release.toml --unreleased | changelog-gh-usernames

This would print the release notes to console, you can pipe it to a tool that copies it to your system clipboard as required.

For the release notes however, there are some cases where we can't consistently obtain GitHub usernames, in which case it would have to be done manually.

Refer to usage information of both of these tools for more complex use cases.

Motivation and Context

Better structured changelogs and release notes.

How did you test it?

Manually.

Checklist

• I formatted the code cargo +nightly fmt --all
• I addressed lints thrown by cargo clippy
• I reviewed submitted code
• I added unit tests for my changes where possible
• I added a CHANGELOG entry if applicable