[improve][doc] Improve the information architecture of encryption and cookbook

[momo-jun]

Motivation

Improve the doc set of the Security chapter to provide Pulsar users with a more accurate, easy-to-understand, and comprehensive information experience.

This is a follow-up PR related to #17615.

It addresses the following main issues:

1. The IA of encryption topic is difficult to understand and follow.
2. The encryption cookbook is a complete duplicate of the above encryption topic.
3. The encryption tutorial is available for Python and Node.js clients, but missing for Java/C++/Go. It also shares the same get-started framework and can be streamlined using code tabs.
4. The security overview lacks focus.

Modifications

1. Re-org the encryption topic and its content.
   -->

2. Streamline the encryption tutorial on various clients and add the contents for Java/C++/Go clients.

3. Replace the original cookbook content with the new tutorial.

4. Improve the security overview by highlighting three pillars: encryption, authentication, and authorization, with links for further reading.

Preview

Security Overview

Encryption

Cookbook

Documentation

• doc

[nodece]

LGTM