Qualification default expiration time

[samuelson-ben]

Hi, here a pr for the topic of the qualification requests.

As part of it, it would be suitable to have a default expiration time in the core so not every plugin as to build it itself.

See also https://github.com/ephios-dev/ephios-qualification-fixtures/pull/7 as the changes for the import repo.

Please look over it and give some feedback.

I know the way I solved the dilemma between having a fixed time and a set at the end of year isn't great but I don't want to introduce many new fields and it should be able to set something like the 15. May of the following year and end of year or month wouldn't be suitable.

I am open for other ideas.