Make tasks groups executable from console

[jensschmeink]

If a task is organized in a task group which might not be the default group (normally the users group) the task cannot be executed in the console application.

This is fixed in this PR. Call the run function now as following: GTlabConsole run (last one is optional)

Description

If the given is not empty the task group is switched to the given group and the task is searched and if found executed. For a cleanup of the batch the functions related to process execution are extracted to new files in a new namespace.

How Has This Been Tested?

Manual tests of execution of a task which is part of another task group

Checklist:

• [ ] A test for the new functionality was added (if applicable).
• [ ] All tests run without failure.
• [ ] The changelog has been extended, if this MR contains important changes from the users's point of view.
• [ ] The new code complies with the GTlab's style guide.
• [ ] New interface methods / functions are exported via EXPORT. Non-interface functions are NOT exported.
• [ ] The number of code quality warnings is not increasing.

[jensschmeink]

Most changed lines are the results of the switch from qDebug to gtLogging and the move of the process execution related functions to new files

[rainman110]

Please append the changelog!