This fixes an issue with `select2('data')` that caused it to not
work as intended. Because we were using `Select2.data` for the
data adapter, it was overriding the `Select2.data()` method which
was supposed to be used.
This just renames the `Select2.data` property to
`Select2.dataAdapter` to prevent the naming collision.
This closes https://github.com/select2/select2/issues/3104.
95be140760