Fix sign in redirect when token is expired

[Betree]

Fix opencollective/opencollective#1797

In #1434 I made some changes to properly redirect a user that would click on a signin link with an invalid token while already being logged in.

However I made a false assumption while working on it as I considered that an invalid token was the same things that an expired token.

As a consequence, the bug would still appear for a user that would click on an old sign in link.

Changes

• On /signin/{token}?next=/, if token is expired, we still try to login with the localStorage token
• Added a cypress helper to generate tokens on the client side
• Added tests that use valid but expired tokens
• Added a assertLoggedIn helper for tests

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[znarf]

@Betree does that take care of the part 2) of the issue (broken redirect in second Sign In attempt?)

[Betree]

@znarf I suspect this issue was because we stored a corrupted token in localStorage (expired tokens were still stored there). So it should normally be fixed.

I've added a test to ensure redirect is properly handled regardless of how next url is encoded.

[Betree]

I've just modified editCollective page to use the new UserProvider to deal with a recurring bug with the getCollectiveToEditData being fired before user was logged in which resulted in random loading errors, particularly on CI.