OFMCC-2048 - add Employee Certificates to Staffing page in Core Application

[vietle-cgi]

Summary of this ticket:

• Add Employee Certificate input to Staffing view and Staffing Summary view
• Add some validations for Employee Certificate: The provider must provide ECE/ECEA certificates for all employees (the number of staff and the number of certificates must match, and there must be no duplicate Initials or Certificate Numbers)
• The max length of Initials is 4, and the max length of Certificate Numbers is 6. Certificate Numbers is a number field