Add ability to hide the process execution info displayed in output panel

[DonJayamanne]

Currently the output panel displays way too much information and this adds a lot of noise that causes issues with the UI tests.

UI Tests monitor the output in the output panel to check whether certain this ran (linters, language server, jedi, etc).

However when we have the process information logged, then there's too much information in the output panel, so much that it always scrolls and using UI tests its impossible to test the contents of the output panel without scrolling (this is too complicated).

Its easier to add a setting to prevent logging of such information into the output panel.

Note: Such a setting is crucial for the UI tests.

Suggestion is to add a setting, but not expose it to users (i.e. theres no intellinsense in package.json - similar to other settings we have in launch.json & settings.json that's not exposed to users but only used for debugging purposes).