Mender does not find mount command when launched through Remote Terminal (PATH issue)

Original discussion on Mender Hub.

The core issue is that the shell is not launched as a login shell, and therefore it does not pick up the default PATH as it should. The solution is to add the -l argument to the shell.

Acceptance criteria:

• ShellArguments key (string list) added to mender-connect.conf.
• Defaults to ["-l"]
• Arguments are used when calling ShellCommand.
• Unit tests
  • Make sure to test when setting it to empty, can easily be confused with the default.
• Documented in https://docs.mender.io/2.6/add-ons/remote-terminal/mender-connect-configuration-file/mender-connect-configuration-options