Adding migration to rename 'housing'... to 'housing-local-services'...

Renaming the tag 'housing' to 'housing-local-services' so 'housing' can be reused as a topic.

There is a Whitehall PR for retagging detailed guides (https://github.com/alphagov/whitehall/pull/1796) and a Router-data PR (https://github.gds/gds/router-data/pull/198) for redirecting the browse categories.
Sure, I'll remove it - that sounds right.