[Feature request] Assign project to task

[Heiss]

All tasks need a project in vikunja. So there is a default project selectable in settings. But what, if you want to change it task-specific?

- [ ] this task is in default project [vikunja_id:: 1]
- [ ] this task is in a custom project [vikunja_id:: 1] [vikunja_project:: 3]
- [ ] this task is in a custom project [vikunja_id:: 1] [vikunja_project:: custom_project]

in the second line, you need to know the id. But in line three, there are more errors likely... how should it communicate such cases, if there are no project with such an id or name? Should be created automatically? Or should the user be asked to confirm the creation? Or an error should happen and sync cannot be finished until the user has created the project by himself?

Any opinions?