Remove empty

Status: **Opened for visibility**
Reviewers: **@scalvert @Helen-Mobify **

## Adds:
- removeEmpty: removes empty elements in the same selection
- tests

Via @Helen-Mobify 's comment in the old PR:

Fix the removeEmpty logic:
Reverse the if condition as it was removing elements that have text

This utils should remove the element if it matches any of the following conditions:
- empty element
- contains &amp;nbsp; or &amp;#160;
- contains &lt;br/&gt; or &lt;br&gt;
Yes. We're mapping so that we can chain to to `.removeEmpty()`. With the map it will return the same selection minus the removed empty elements.