Add missing security prerequisites for OIDC and document alternative ESM command for the x509 internal mapper

[taban03]

• Add missing security prerequisites for OIDC
• Document alternative ESM command for the x509 internal mapper
• Modify note in the X.509 Client Certificate Authentication article for v3 to specify that the internal mapper API is the default method.
  The changes are apply on both v2 and v3

[github-actions]

😺 Thank you for creating this PR! To publish your content to Zowe Docs, follow these required steps.

• Add the label review: doc.
• Identify your content topic with a label. (Examples: area: apiml, area: cli, area: install and config, etc.)
• Specify the major Zowe release(s) for your content. (Examples: release: V1, release: V2, release: V3)
  • If adding content that needs to be removed from V3 documentation, add the V3 N/A tag.
• Select the master branch if your PR updates content that is on the live site. Select docs-staging if your PR updates content for a future release.
• Notify the Doc Squad about this PR. If you don't know whom should review your content, message the #zowe-doc Slack channel. If you know which Doc Squad writer should approve your content, add that person as a reviewer.

Need help? Contact the Doc Squad in the #zowe-doc Slack channel.

[github-actions]

📁 The PR description is missing the file name(s) for the updated content. List all the files included in this PR so this information displays in our Zowe Docs GitHub Slack channel.

If you have addressed this issue already, refresh this page in your browser to remove this comment.

[github-actions]

🔍 The review label is missing. Add a review: label so we can determine who needs to approve this PR.

If you have addressed this issue already, refresh this page in your browser to remove this comment.

[github-actions]

💾 The release label is missing. Add a release: label so your content is published with the correct major Zowe release.

If you have addressed this issue already, refresh this page in your browser to remove this comment.

[github-actions]

📌 The subject area label is missing. Add an area: label so we know what your content is about.

If you have addressed this issue already, refresh this page in your browser to remove this comment.

[github-actions]

🚀 Deployed on https://66ffcaa821190603fa895610--zowe-docs-master.netlify.app