Code cleanup, remove inline javascript in DOM element, move error messages constants to globals.html, remove html DOM dependent traversal for data retrieval, refactored how we determine if the checkbox is checked or not

GCP-9940

Reviewer: Chezka Arevalo
Move message constants from specifyLabelDetails.html to this file

GCP-9940

Reviewer: Chezka Arevalo
Added checking, if there is only 1 checkbox either for nursery or trial, then we automatically check the checkbox

GCP-9940

Reviewer: Chezka Arevalo