implement round for number field elements with real embedding #21935
Description
Real embedded element has a floor and ceil but no round (= nearest integer)
sage: a = QuadraticField(2).gen()
sage: a.floor()
1
sage: a.ceil()
2
sage: a.round()
Traceback (most recent call last):
...
AttributeError: 'sage.rings.number_field.number_field_element_quadratic.NumberFieldElement_quadratic' object has no attribute 'round'
Depends on #22095
Component: number fields
Keywords: days79
Author: Vincent Delecroix
Branch/Commit: 720f040
Reviewer: Jean-Philippe Labbé, Sébastien Labbé
Issue created by migration from https://trac.sagemath.org/ticket/21935