Twig Filter "spaceless" is deprecated

Problem/Motivation

%Since twig/twig 3.12: Twig Filter "spaceless" is deprecated%

Steps to reproduce

Proposed resolution

Create a Twig extension in Drupal that provides the spaceless filter as BC, without triggering the deprecation notice.

Follow up to remove use of the spaceless filter in core templates: #3486170: Remove use of deprecated "spaceless" filter in core templates

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet