RK-A2

Currently we receive a question number in the format <chapter>.<exercise num>.<question num>. List of such question numbers is used to map:
1) Chapter to a list of exercises
2) Exercise to a list of questions
These lists are then used in their corresponding dropdowns

Going forward we have question numbers in the new format <chapter>-<section num>-<exercise num>-<type>-<difficulty>-<question num>. Write a separate logic to parse a list of such question numbers and map:
1) Chapter to a list of sections
2) Section to a list of exercises
3) Exercise to a list of questions
These list should facilitate the 'Section' dropdown that will be added by ticket http://34.67.50.25/issues/3747

Note: For grade 5 and 6, the current logic should be maintained. Only for grades other that these should be using the new logic.