Fix bookmark action
Summary: Adds tootip, different icons depending on checked state and fixed functionality
Test Plan:
- Open a document
- click bookmark action
- the bookmarked page should appear in the bookmarks tab of the contextDrawer
Reviewers: Okular, Plasma:_mobile, ngraham
Reviewed By: ngraham
Subscribers: ngraham, okular-devel
Tags: Okular
Differential Revision: https://phabricator.kde.org/D22904