feat: Flashing error message on server error

[freaky4wrld]

Fixes #1569

What changes did you make and why did you make them ?

• Added a file name snackbarContext.js to client/src/context, the file is a context for the Snackbar component as per the requirement in the issue......
• Removed the setEventAlert functionality and using Snackbar component added the functionality of adding alerts like
  - Event Created alert to recurring event
  - Event Updated alert when the recurring event is updated
  - Event Deleted alert when the recurring event is deleted

Screenshots of Proposed Changes Of The Website (if any, please do not screen shot code changes)

[github-actions]

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[freaky4wrld]

@Spiteless the alert on recurring event has been provided, please have a look, also please tell what to do whether to update alert for Event Updated/Event Deleted for severity=success or let it as it is ?

[Spiteless]

This is looking very good. Thank you for your hard work!

Requested a few small changes to create more clarity.

Very close to merging!

[freaky4wrld]

@Spiteless made the suggested changes, please check!!!