Move tasks while deleting event type (#229)

[Aga-C]

What is it?

• [x] Bugfix
• [ ] Feature
• [ ] Codebase improvement

Description of the changes in your PR

• Changed moving logic to move also tasks while removing event types.
• Also modified function checking if there's anything in an event type.

Before/After Screenshots/Screen Record

• Before:

https://github.com/FossifyOrg/Calendar/assets/85929121/8a45738c-01e0-4a6a-ad4b-d2d7cf04a6ec

• After:

https://github.com/FossifyOrg/Calendar/assets/85929121/bde8b966-c98b-4b52-b824-88ac1ddf0f30

Fixes the following issue(s)

• Fixes #229

Acknowledgement

• [x] I read the contribution guidelines.