HTMLForm: Use OOUI\Element::configFromHtmlAttributes instead of rolling our own

HTMLForm: Use OOUI\Element::configFromHtmlAttributes instead of rolling our own

Depends on I0e5c956b9358b510c8473b1cfe6465ea1b5c07ef in OOjs UI.

This mostly reverts dd04b310527c3ce69911789254939e9a2b627ada and parts
of e85bd04bcd26f9a05406cedf6ee0dcac0b54c435.

In addition to cleanup, it fixes bugs in HTMLFormFieldWithButton
(which did not add some attributes in OOUI mode) and HTMLMultiSelectField
(which did not do the mapping, losing some attributes in OOUI mode).

Change-Id: I0d1a5288e9edb73a0c3a8431feca9fcc67b72b6a