Adds tests for conversion of a Number whose corresponding toString() value
is a valid ISO string. For some Temporal types this is possible, with a
number like 20220418.
Especially for Temporal.Calendar, we have to take into account the case
where the number is provided as the value for the 'calendar' property in a
property bag, and the case of up to one level of nested property bag as
well.
Regularizes and expands existing tests for this case.
