feat: add feature flag to support rustls-tls for rust client

[ameijboom]

Due to the dependency on reqwest with it's default options, we have no way to replace openssl with rustls, which is an issue for our projects.

With this PR, I've added a feature flag that replaces openssl with rustls, while leaving the default on openssl. This ensures no breaking changes with previous versions and allows anyone to choose between their preferred TLS library.

Checklist

• I have read the contributing guidelines
  and signed the CLA.
• I have referenced an issue containing the design document if my change
  introduces a new feature.
• I have read the security policy.
• I confirm that this pull request does not address a security
  vulnerability. If this pull request addresses a security vulnerability, I
  confirm that I got approval (please contact
  [email protected]) from the maintainers to push
  the changes.
• I have added tests that prove my fix is effective or that my feature
  works.
• I have added the necessary documentation within the code base (if
  appropriate).

[aeneasr]

Hello, the same limitation applies as with the other repository. The files changed here are also auto-generated.