Adding support for protocol handler

[marcellintacite]

Here's a draft for this issue : #1247
This merge request adds support for handling xmpp: protocol links in Converse.js, allowing users to click links like xmpp:user@example.com to automatically open a chat with the specified JID if logged in. This enhances user experience by enabling seamless integration with external XMPP links (e.g., from emails, websites, or other apps).

Before submitting your request, please make sure the following conditions are met:

• Add a changelog entry for your change in CHANGES.md
• When adding a configuration variable, please make sure to
  document it in docs/source/configuration.rst
• Please add a test for your change. Tests can be run in the commandline
  with make check or you can run them in the browser by running make serve
  and then opening http://localhost:8000/tests.html.

[jcbrand]

Looking good so far @marcellintacite!

Please also remember to update the DOAP file to mention support for the new XEP
https://github.com/conversejs/converse.js/blob/master/conversejs.doap

[marcellintacite]

@jcbrand Hello, i would like your review for the test i wrote

[marcellintacite]

@jcbrand i need your help on tests so i can get done with this PR. I am facing some errors

[marcellintacite]

Hello @jcbrand i have fixed test issue