4g coverage (#247)

* Add files via upload

Add QA'd csv file produced December 2024

* Add files via upload

Update 4g-coverage.csv with new version.

* Updated Joson with new dates and url for latest source

* Removed blank row in csv

* Removed blank row from csv

* Update 4g-coverage.json

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Co-authored-by: NickR-ONS <nick.richardson@ons.gov.uk>
Co-authored-by: Sazzadur Rahman <110844828+sazzadur-ons@users.noreply.github.com>