Add TeXstudio support
Summary:
Some people need it because it is now the default TeX editor in distributions.
BUG: 404120
Test Plan: "Settings -> Configure Okular... -> Editor -> TeXstudio". Should work for the reverse search if the tex file is compiled with \usepackage[active]{srcltx}
Reviewers: Okular, ngraham
Reviewed By: ngraham
Subscribers: ngraham, okular-devel, kde-doc-english
Tags: Okular, Documentation
Differential Revision: https://phabricator.kde.org/D19272