Add class method Decimal.from_number()

[serhiy-storchaka]

Feature or enhancement

It is an alternate constructor which only accepts a single numeric argument. Unlike to Decimal.from_float() it accepts also Decimal. Unlike to the standard constructor, it does not accept strings and tuples.

Similar to float.from_number() and complex.from_number() (see #84978) and Fraction.from_number() (see #121797).

Linked PRs

• gh-121798: Add class method Decimal.from_number() #121801