Add script to fix which schools are attributed to BLMK and N&W#5157

MartinVanIJcken merged 2 commits intonextNHSDigital/manage-vaccinations-in-schools:nextfrom

fix-blmk-nw-schoolsNHSDigital/manage-vaccinations-in-schools:fix-blmk-nw-schoolsCopy head branch name to clipboard