Multiselect directories

[rajb957]

Multiselection of folders while selecting folders

Description

In the source, multiple folders cant be selected, due to some limitations in QFileDialog. This pull request solves and allows multiselection of folder everywhere where folders need to be selected Fixes #1869

Motivation and Context

It would be more convenient if one can select multiple directories in one go, not having to open add folder dialog window multiple time, saving previous time and clicks.

How Has This Been Tested?

By running them locally in my system. No actual tests edited so far.

Screenshots (if appropriate):

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [x] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] I have read the CONTRIBUTING guide.
• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.

I provide my contribution under the terms of the license of this repository and I affirm the Developer Certificate of Origin.

[rajb957]

The solution implemented is adapted and iterated upon from a method discussed on Stack Overflow for enabling QFileDialog to select and return multiple folders. For further details, see the discussion here.

[sayem314]

Thank you for your PR but this seems like a duplicate of https://github.com/borgbase/vorta/pull/1871

[m3nu]

This isn't optimal either: Now we have 2 different dialogs. Native one and the one from Qt.

Would be best to have only one dialog for files and folders, including multiple ones.