A button is easier for the user to discover than a keyword action.
There is a small risk that user does not group the processing of payments but
it existed also wizard the keyword action and it is compensated largely by the
benefit of discoverability.
The fiscal years are created centered on the passed date such that if the
current day change during the execution, the fiscal year is still usable.
Also fiscal year can be created for a range of dates such that it is guarantee
that the dates are in the fiscal year.
And finally remove datetime and dateutil import when they are not used.
Closes#9977
Cédric Krier