add activity log to expense form

[ChristopherJohnston]

Added a list of activity for the current expense in the edit expense form. This makes use of the recent merge of #141, which added a basic activity log.

I have chosen to create new ExpenseActivityList and ExpenseActivityItem components rather than re-use ActivityList and ActivityItem so they can be extended in future to include, for example, a summary of what exactly was changed in the update.

This PR closes #160.

No Activity

Activity List

[ChristopherJohnston]

ok after a few attempts I think I got this back up to date!

[ChristopherJohnston]

@scastiel this is ready to go unless you have other comments.

[ChristopherJohnston]

@scastiel bump 😀

[ChristopherJohnston]

Closing to re-visit after comments feature is merged