In past versions of Select2, the `width` option could be used to
tell Select2 how to determine the width of the container generated
by Select2.
**Breaking change:** The default value for the `width` option has
been changed from `copy` to `resolve.`
**Breaking change:** The old option called `copy` has been renamed
to `style` to better reflect what the width is generated from.
This fixes https://github.com/select2/select2/pull/2090.
This fixes https://github.com/select2/select2/issues/2911.
