Add Tasks view

### How to use GitHub

* Please use the 👍 [reaction](https://blog.github.com/2016-03-10-add-reactions-to-pull-requests-issues-and-comments/) to show that you are interested into the same feature.
* Please don't comment if you have no relevant information to add. It's just extra noise for everyone subscribed to this issue.
* Subscribe to receive notifications on status change and new comments.

**Is your feature request related to a problem? Please describe.**

Users of my NC want their info in one easy to use app, and as it stands they need this app, f-droid, davx5 and a separate calendar app.
I am not even going to try to get them to install and learn a whole new app for tasks. They use Google calendar with davx5 now, but it does not sync tasks to Google calendar.
If I somehow convinced them to get a tasks app, that would be 5 apps to just get a calendar, tasks, and file sync.
* Even though I really like the software and the work you have done.

**Describe the solution you'd like**

I would like an integration of the tasks app, even if it is a simple one.
A calendar would be nice too; someone just told me it would be nice if it was all in one.

**Describe alternatives you've considered**

Just use the Google calendar.

**Additional context**

I'm trying to figure out any way to have the apps be more user friendly to my cloud users and I think this will help me by at least have 1 more app be easily accessible.