fix: Learners can't sync courses to calendar on iPhone

[shafqat-muneer]

Description

LEARNER-9807
Prior to this update, individuals using iPhones with iOS 17 or later were unable to synchronize courses with the calendar on their devices. The problem stemmed from the utilization of a deprecated function for accessing calendar events permissions.

Deprecated Function of EKEventStore:

requestAccess(to:completion:)
For iOS 17 and subsequent versions, utilizing this method does not trigger an access prompt; instead, it promptly invokes the completion block with an error.

Within this pull request, we have incorporated a new method for the EKEventStore that is compatible with iOS 17 and later versions.

requestFullAccessToEvents(completion:)

Additionally, included the NSCalendarsFullAccessUsageDescription key in the Source/edX-Info.plist file.

How to test this PR

• To assess this pull request, it is necessary to possess an iPhone running iOS 17 or a newer version. Navigate to any course and access its dates section for testing.
• Enable the "Sync to calendar" option, and you should observe a prompt requesting calendar permissions.

[saeedbashir]

LGTM 👍