Refactors RDP tunnel logic to streamline and unify handling

[aschumann-virtualcable]

This pull request refactors and simplifies the Linux tunnel scripts for both the RDP and RDPEmbedded transports. The main focus is on improving tunnel initialization, streamlining client launching logic, and updating the process for starting tunnels and handling RDP connections. Significant cleanup removes redundant code and aligns parameter naming conventions for better maintainability.

RDP tunnel script improvements:

• Changed the order of searching for RDP client executables to prefer xfreerdp2 before xfreerdp, ensuring compatibility with newer versions.
• Updated the Tasks.startTunnel invocation to use a single object parameter with clearer, more descriptive field names (addr, port, ticket, startup_time_ms, check_certificate, shared_secret), improving readability and maintainability.

RDPEmbedded tunnel script simplification:

• Removed all logic related to finding and launching local RDP client executables, as well as handling temporary RDP files and parameter expansion. Now, the script simply starts the tunnel and invokes RDP.start(data), delegating connection handling to a uds launcher rdp embedded.
• Updated logging to provide clearer information about tunnel establishment and removed unnecessary error messages about missing RDP clients.

Signature updates:

• Updated the signature files for both tunnel scripts to reflect the code changes. [1] [2]