Support managing apps (pacticipants) via UI

[YOU54F]

There's currently no way to manage apps via the UI, it would be nice to be able to do so. There's an endpoint already in the API (pacticipants).

Currently admins and teams are able to manage everything via the UI with proper access control via roles, but apps are still something that we create using the API, which is a bit awkward.

https://pact.canny.io/admin/board/feature-requests/p/support-managing-apps-pacticipants-via-ui

This issue has been linked to a Canny post: Support managing apps (pacticipants) via UI 🎉

[YOU54F]

Relates to pact-foundation/roadmap#81