### What?
Previously, setting the `admin.rows` property did not change the height
of the `textarea` field input.
### Why?
Although `rows` was being properly set on the textarea element - it's
absolute positioning prevented the height from actually changing.
### How?
Updates the styles of the textarea field component to properly allow the
rows prop to change the height of the field.
Example w/:
```
{
name: 'someTextArea',
type: 'textarea',
admin: {
rows: 5,
}
}
```
Before:

After:

Fixes#10017