Add automated unit tests for UI endpoints

[Kaptard]

I'm submitting a...

• [ ] Bug report
• [x] Feature request
• [ ] Documentation issue or request

Current behavior

There's only a single UI page check (/warframe)

Expected behavior

Should check every single page to see if it loads at all, pretty much like we do for API endpoints.

Minimal reproduction of the problem

Environment

Browser:

• [ ] Chrome (desktop) version:
• [ ] Chrome (Android) version:
• [ ] Chrome (iOS) version:
• [ ] Firefox version:
• [ ] Safari (desktop) version:
• [ ] Safari (iOS) version:
• [ ] IE version:
• [ ] Edge version:

For development issues:

• Node version:
• Operating System:

Additional Description