Brief overview of PR changes/additions

Description:

This pull request adds support for telnet:// links to Mudlet. This allows users to click on telnet:// links in other applications and have them open in Mudlet.

The following changes were made:

• Added a MudletApplication class that inherits from QApplication to handle FileOpen events.
• Added a handleTelnetUri function to the mudlet class to parse telnet:// URIs and open a new profile or connect to an existing one.
• Added a dialog to ask the user if they want to set Mudlet as the default telnet client.
• Added a “Check if Mudlet is default client” checkbox to the profile preferences.
• Modified the main.cpp file to use the MudletApplication class.
• Modified the mudlet.pro and CMakeLists.txt files to include the new files.

Motivation for adding to Mudlet

I want to contribute and solve bounties

Other info (issues closed, discussion etc)

/fixes #689 /claim #689