Syntax of list comprehensions / container aggregates

[treiher]

The current syntax of our list comprehensions deviates from Ada 202X container aggregates.

Current

for ELEMENT in SEQUENCE => EXPRESSION when CONDITION

Ada 202X

for ELEMENT in SEQUENCE when CONDITION => EXPRESSION

RecordFlux

for ELEMENT in SEQUENCE if CONDITION => EXPRESSION

I think we should use the same syntax as Ada 202X if we do not have a good reason for the deviation.