timeout options for waitForTwoFACode should be a real timeout

[gregorylegarec]

As we worked on Dummy TwoFA konnector with @y-lohse, we realized that the timeout option in function waitForTwoFaCode was not a real timeout but a kind of endTime instead : it's expecting a dateTime in the future, not a given amount of seconds to wait.

[doubleface]

I agree this was a bad choice indeed. Let's add an endTime alias for this option and mark the timeout option as deprecated. I have the same issue for the saveFiles function from cozy-konnector-libs