Save draft feature

A/C:
1. Activity card appears as a standard activity card but with icon wrapped on dotted border and white background (maybe can do as a status colour).
2. Any activity of the category that has draft status will have save as draft button in the activity modal/pane.
3. Clicking on the save as draft button will save the activity with a draft status without triggering the sending action if it is a communication type (e.g. email).
4. We can implement all points above for communication category only to start with if draft status is not forbidden to other categories.