feat: Create libsoup 3.0 samples

[colinkiama]

Description

Helpful for people who want to do web client/server operations.

Possible Solutions

No response

Additional Info

Retired GNOME Vala wiki had a libsoup 2.4 same guide: https://wiki.gnome.org/Projects(2f)Vala(2f)LibSoupSample.html

[colinkiama]

These examples need to be updated to interact with more relevant/up-to-date services:

• GNOME Twitter Status Example -> GNOME Mastodon (ActivityPub) Status Example - https://floss.social/@gnome
• Synchronous HTTP Request example -> https://vala.dev Synchronous HTTP Request example (So we don't need http auth. Just focus on the synchronous request)
• Simple (XML) server example -> Simple JSON server example

Drop the XMLRPC examples.

Also, we might need to consider CORS too in these examples if they aren't working by default.