645 foster index

[mononoken]

🔗 Issue

#645

✍️ Description

This PR adds the ability for staff to create fosters and manage existing fosters. Most of the action happens on the fosters index that has been added to the sidebar. There is a decent amount of other things touched by this, such as Pets now being able to have multiple Matches.

I made comments for spots that deserve some attention from reviewers. Let me know if you have any questions!

One to do related to this: We need to add new emails for fosters and logic to send the correct email.

I think we should remove the callback from the model and put the respective email sends in the controller actions they belong to. The model callback was fairly annoying while testing on this PR.

📷 Screenshots/Demos

https://vimeo.com/949462228?share=copy