fix(cdk/drag-drop): error when cloning file input with value (#20793)
fix(cdk/drag-drop): error when cloning file input with value (#20793)

When we clone the dragged element to generate its preview, we transfer the values of
inputs so that they look identical. The problem is that assigning the value of a `file` input
will throw an error so we have to skip it.

**Note:** does not include a unit test, because we can't set the of a test element programmatically.

Fixes #20783.
DevVersion/material2,angular/components,crisbeto/material2,mmalerba/material2,DevVersion/material2,josephperrott/material2,mmalerba/material2,angular/components,crisbeto/material2,DevVersion/material2,andrewseguin/material2,mmalerba/material2,josephperrott/material2,DevVersion/material2,mmalerba/material2,DevVersion/material2,andrewseguin/material2,angular/components,crisbeto/material2,crisbeto/material2,angular/components,andrewseguin/material2,josephperrott/material2,josephperrott/material2,andrewseguin/material2,andrewseguin/material2,josephperrott/material2,mmalerba/material2