Permitting users to add candidates only prior to Election date and time

Description

Prior to this MR, users were able to add candidates inside election even during and after the commencement of the election. To prevent user from adding more candidates after commencement of election, I disabled the "Add Candidate" button and provided another modal that explains why user has not been able to add candidate for that election.

Here are the images from UI side.

1. Images when Election is not started or commenced. Condition is current datetime < election datetime

2. Images when Election is started or commenced. Condition is current datetime >= election datetime

Type of change

Please mark the options that are relevant.

• Updated UI/UX
• Improved the business logic of code
• Added new feature
• Other

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings