[Enhancement] Add a way for Custom Actions to display output (even on success)

[goran-w]

Sometimes we may want a Custom Action to simply show some output to the user.

Here's a simple example, where I tried to make an Action that shows me the value(s) of a specific git-config variable. (And yes, there may be multiple values, in the system, global and local config-scopes.)

When running this Action, it pops up an output panel which disappears very quickly (since the command is successful). To fix this, I could try making the command output a failure exit code to keep the output/notification panel open, or I could go to View Logs to see the output, but both methods are cumbersome and indirect.

Perhaps the simplest fix would be to add a checkbox 'Keep output open on success' (or similar), to make sure I get time to read the (successful) output from the Action's command.