Fix task list click issues

[planarvoid]

Fix

The task list is facing some issues when the checkbox is clicked. In this PR these should be fixed.
The issues are when you add an item in the middle of the task list or when you try to click on an empty item at the end of the list. Please check whether the task list works as expected (if you can think of other test scenarios).

Test 1

1. Create a task list with multiple items
2. Add an item in the middle of the list
3. Try checking/unchecking the item and all the items around it
4. Confirm that the items are checked correctly

Test 2

1. Create a task list with multiple items at the end of the document
2. Add an empty item at the end of the list
3. Move cursor in one of the non-empty items
4. Click on the empty item checkbox
5. Notice it gets checked correctly

Review

@AmandaRiu

Make sure strings will be translated:

• If there are new strings that have to be translated, I have added them to the client's strings.xml as a part of the integration PR.

[AmandaRiu]

Works great @planarvoid!