API moved to /v1

[csc-felipe]

Proposed solution

There are some more breaking changes in the backend from this PR CSCfi/metadata-submitter#476

• API is now under /v1
• /logout doesn't redirect to frontend any more, it returns 204
• Only API routes are checked for session authentication, so frontend now has to check it. Other routes are public

Public routes are:

• /aai
• /callback
• /logout
• /health
• /static
• / - with catch-all, so any routes not matching other routes will return the frontend files, so maybe frontend needs to handle routing differently

DoD (Definition of Done)

Frontend works against backend commit be0002c, which is the last commit in develop at the time of creating this issue.

Testing

Tests pass again ^^