Refactored CustomAlerts UI to support selection of medium to send alert, #PG-4530#208

AltamashShaikh merged 3 commits into5.x-devmatomo-org/plugin-CustomAlerts:5.x-devfrom

PG-4530-refactor-UImatomo-org/plugin-CustomAlerts:PG-4530-refactor-UICopy head branch name to clipboard