add remove calendar event to CalendarExtensions

[AntekOlszewski]

Fixes #1962

• I have read the Contribution Guidelines
• I have checked that there isn't already another pull request that solves the above issue
• All newly added code is adequately covered by tests
• All existing tests are still running without errors

Changes

This change was previously proposed in #2062 but was closed without merging because of formality reasons (original PR didn't use PR template).
This PR reintroduces the same feature on top of the current codebase.

• Added 4 overloads of RemoveCalendarEvent to CalendarExtensions in Calendar.cs:
  1. RemoveCalendarEvent(DateTime date)
  2. RemoveCalendarEvent(string description, DateTime date)
  3. RemoveCalendarEvent(int year, int month, int day)
  4. RemoveCalendarEvent(string description, int year, int month, int day)
• Added 4 unit tests covering removal by date, by year/month/day, by description, and no-op when event doesn't exist

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Please upvote 👍 this pull request if you are interested in it.

[patriksvensson]

LGTM 👍

[patriksvensson]

Merged! Thank you for your contribution. Much appreciated! 👍