When changing to uppy for file uploads we forgot to add
these conditions to the paste event from 9c96511ec4
Basically, if you are pasting more than just a file (e.g. text,
html, rtf), then we should not handle the file and upload it, and
instead just paste in the text. This causes issues with spreadsheet
tools, that will copy the text representation and also an image
representation of cells to the user's clipboard.
This also moves the paste event for composer-upload-uppy to the
element found by the `editorClass` property, so it shares the paste
event with d-editor (via TextareaTextManipulation), which makes testing
this possible as the ember paste bindings are not picked up unless both
paste events are on the same element.
9fc33d310b