fix(exercises): :bug: Swiping to delete an exercise only deletes the exercise from the list and not from the app

[samuelsainz]

Description

When deleting an exercise from the list using the swipe gesture, the exercise was not only deleted from the list but from the "All exercises" list.

Fixing it so it only deletes the exercise from the list but it is still available to be used again in any of the lists.

Related Issue

Closes #68

How Has This Been Tested?

When deleting an exercise from the list, if you then go check the list of exercises, the exercise is still there.

Screenshots (if appropriate):

N/A

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Developer tooling (fix or improve developer tooling)

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [x] All new and existing tests passed.