Fix convert folders and open from outline

[vkbo]

Summary:

This PR fixes two issues:

• The convert to document/note menu entries in the project tree were still trying to convert files even if it was applied to a folder. They now properly call the convert folder function when used on folders.
• Trying to open a document from outline view should switch focus even if the document is already open.

Related Issue(s):

Closes #1291
Closes #1305

Reviewer's Checklist:

• The header of all files contain a reference to the repository license
• The overall test coverage is increased or remains the same as before
• All tests are passing
• All flake8 checks are passing and the style guide is followed
• Documentation (as docstrings) is complete and understandable
• Only files that have been actively changed are committed