[HOLD] [ENG-8975] Redirect addons support

[futa-ikeda]

• Ticket: [ENG-8975]
• Feature flag: n/a

Purpose

• Provide support for redirect services (port of this ember PR )

Summary of Changes

• Add redirect addon model
• Add new service type to existing addons enums, code, etc
• Add support for finding redirect addon types on the addons page
• Update addon terms page to handle redirect to redirect addon URL

Screenshot(s)

Updated Addons Terms page to show "Go to {ServiceName}" button, which should open a popup window that will take users to the URL shown at the bottom of the screen, as well as a link in the description that will take user to the same place in case the popup window is blocked

Side Effects

QA Notes

[futa-ikeda]

Needs to be released in tandem with this GV feature: CenterForOpenScience/gravyvalet#335