Fix TERM env argument being misplaced in Flatpak
This MR is identical to !1052 (closed), except it does not use master as the fork branch. Again, I am sorry for the clutter.
Currently, on the Konsole master branch, it only works as intended if the user has only the binary as the start command (e.g. /bin/bash).
Instead of passing the start command args to KSandbox::makeHostContext,
this will append them to the ones returned by makeHostContext on the
'postProcessArgs' function.
In case Konsole is being run as a Flatpak, all of said args would be
added after --env=TERM=xterm-256color
and the program name.
An alternative would be to modify KSandbox::makeHostContext behaviour, but that would require more work to be done. With this MR I intended to fix the issue whilst making the least possible number of changes to the codebase.