Add docs for enterprise_sso and update examples

[Nikpolik]

Important

🔎 Previews:

• https://clerk.com/docs/pr/1770/docs/references/javascript/sign-in/authenticate-with
• https://clerk.com/docs/pr/1770/docs/references/javascript/sign-up/verification
• https://clerk.com/docs/pr/1770/docs/references/javascript/sign-up/authenticate-with#authenticate-with-redirect
• https://clerk.com/docs/pr/1770/custom-flows/enterprise-connections

⚠️ Needs https://github.com/clerk/clerk/pull/857 merged for redirects

Explanation:

The saml authentication strategy has been superseded by a new enterprise_sso strategy that also allows for authentication with OIDC compatible providers besides SAML.

This PR:

1. Adds enterprise_sso as a valid strategy for "authenticateWith" documentation and a deprecation warning in SAML
2. Updates custom flows examples to use enterprise_sso

Checklist

• I have clicked on "Files changed" and performed a thorough self-review
• I have added the "deploy-preview" label and added the preview link(s) to this PR description
• All existing checks pass

[github-actions]

Hey, here’s your docs preview: https://clerk.com/docs/pr/1770

[alexisintech]

posted my code review - let me know if it looks okay :)

[Nikpolik]

@alexisintech ty for taking the time to improve this and adding the redirect (I didn't think about it sorry 🙏). ! Everything looks good 😄

[alexisintech]

amazing! thank you, and lets ship 😸💖