move ContentLanguageSettings::loadByEntityTypeBundle to the storage handler

Problem/Motivation

Typically loadByFoo() methods are on the entity storage handler rather than static methods on the entity class. E.g. loadByProperties() etc.

Steps to reproduce

Proposed resolution

Add loadByEntityTypeBundle() to the storage handler.
Deprecate the entity class static method.

Remaining tasks

User interface changes

API changes

Deprecated method.

Data model changes

Release notes snippet