xdg-utils not installed by default on Ubuntu server

[fharper]

xdg-utils not installed by default on Ubuntu server, so when using the temporary GitHub Access Token, trying to open the browser give this error Error: exec: "xdg-open": executable file not found in $PATH, and the kubefirst cluster creation stop there.

We should probably validate if this binary is installed or in the path, and if not, let the user know they have to open the GitHub page themselves, and continue the process once they confirmed they gave kubefirst access.