This PR adds UI support for marking saved filters as favorites. The backend already supports the `is_favorite` field for saved filters, but the frontend didn't expose this functionality. Users can now favorite/unfavorite saved filters just like regular projects.
This change introduces an expand query parameter which, when provided, allows to return all projects with the max right the current user has on that project. This allows to show and hide appropriate buttons in the frontend.
Resolves https://github.com/go-vikunja/vikunja/issues/334
Previously these store methods created multiple edits on deep objects in the store or edited a deep nested object directly.
This is bad because:
- multiple edits lead to multiple triggers of all the watchers on the project.
- in theory we should listen deep to a project if we use some deep reactive value of a project, if we want deep updates. Because this is easy to forget, it's better to update the project directly. For this the method `setProject` already existed in the store. This is no real overhead because Vue is smart enough to only trigger listeners that use data of the modified state.
By modifying only a copy of the view and submitting the modified result __once__ we can save us a lot of headache.
PS: I'm not sure if there were any visible problems, because Vue is really fast and the reactivity system works quite well. Regardless of this we should try not to modify state unnecessarily.