add ability to search by requisition id

[KarHarker]

To do's:

• [x] update the active/inactive EMS ID list as per Mike Sokal email
• [x] add requisition id to wq_col function to make this a default column
• [x] add option to filter by req_id in filter_ems_data()
• [x] create similar function to lt_lake_sites() but for searching by req ID instead of ems ID
• [x] update tests
• [x] create tests for helper functions
• [x] Update NEWS.md
• [x] Add section on lakes helper functions to README.md