Default sort projects alphabetically if no order set

[lalgee]

User story/persona
As a community manager, I want projects to automatically sort on the campaign page in a useful order for volunteers even if no other order is specified.

Is your feature request related to a problem? Please describe.
When #1493 was implemented, it removed alphabetical sort for campaigns, causing them to appear in random order if one is not set. Community managers do not want to always have to set an order for campaigns.

The sort priorities for projects within a campaign should be:

1. By project ordering number
2. Alphabetically

The sort priorities for projects within a topic need to include an additional element since projects from different campaigns may have the same number. We hope the order below will ensure materials from the same campaign are grouped together. It should be:

1. By campaign name
2. By project ordering number
3. Alphabetically

Acceptance Criteria
Community managers can set the numerical order in which campaign projects appear to on the public using the Projects dashboard in the Django admin by entering the number order in which they want it to appear. In campaigns, projects should be sorted by ordering number and then alphabetically. In topics, projects should be sorted by campaign name, then order number, then alphabetically by project title.

Acceptance Test:

1. Log into Django admin
2. Go to projects dashboard
3. Reorder 2 Blackwells projects.
4. Check the Blackwells campaign to confirm that the projects are sorting as described above.
5. Check the suffrage topic to confirm that the projects are sorting as described above.

[lalgee]

Tested and accepted!

One note that in Topics the projects are sorting into campaign groups but the campaign groups are not sorted alphabetically by title (for example, Anna Dickinson projects are not the first to appear in suffrage) HOWEVER it is working well without that added layer. So CM's are happy with the current functionality and I'm going to close.