In-Band Registration Extension - Base Implementation

[vsevex]

This issue refers to the changes to the working mechanism of the Extension globally, and the implementation of the In-Band Registration Extension. Furthermore, enhancements on the Echo package took place. Two new enums are added for registration process indication.

Changes Made:

• Integrated the extension to be attachable, similar to other extensions.
• Modified main variables and functionalities to work with the main class seamlessly.
• Unlike other extensions, the changes in this extension directly affect the main class as they are made on the main variables. This design choice was made to ensure seamless integration and optimal performance.

Current Status:
As of now, this extension is almost finished, but there is no formal documentation available yet.

Importance and Impact:
The In-Band Registration Extension is an essential feature that allows users to register XMPP accounts directly from the client. This enhancement streamlines the account creation process and improves the overall user experience.