[7.x] Convert Index Templates API routes to snakecase. (#68463)#68653

cjcenizal merged 2 commits intoelastic:7.xelastic/kibana:7.xfrom

cjcenizal:backport/7.x/pr-68463cjcenizal/kibana:backport/7.x/pr-68463Copy head branch name to clipboard