Improvements to existing features

• [Proctoring & Reviewing] Make it easier to switch roles as a proctor or reviewer with multiple roles, by landing on the home page after logging in so that a user can choose their role before entering a proctoring or reviewing session.
• [Proctoring] Ensure that it's possible to pre-assign users with the proctor or global_proctor role, even if they have switched to a different role

Bug fixes

• [Admin] Ensure instructions for students and reviewers don’t contain HTML tags when copy & pasting, as that can mess up how the content is viewed by end-users.
• [Admin] Ensure that the tawk URL in the institute settings has the correct format, avoiding issues where test takers don’t get a support chat box due to an invalid URL.