Modify remote agent install UI and make userfriendlier error messages

[BZ 1131495] Refactor SSHInstallUtility to catch error messages and throw exceptions if operations fail, instead of returning just Failed text

[BZ 1132051] Catch scp errors when installing to get proper error message for missing permissions.

[BZ 1128772] Catch some basic error messages and create a friendlier layout for them

[BZ 1128779] After the agent has been installed, refresh the UI to show only relevant information.

[BZ 1128782] While installing, show window which indicates the installation is running