[TASK] Added original news templates / partials

Since the teaser rendering will not be moved to a partial in the
upstream repository we maintain our own modified copies of the list
item partial and the detail template.
[TASK] Updated / override news templates / partials

The news list item partial and the news detail template are now
overwritten and implement a custom teaser rendering.
[TASK] Use new TCA override config

Since the news extension now uses the new TCA handling we can use the
new TCA override handling for improved performance.