revert(select): avoid checking option element selected properties in render

This reverts commit dc149de9364c66b988f169f67cad39577ba43434. That commit fixes a bug caused by
Firefox updating `select.value` on hover. However, it
causes other bugs with select including the issue described in #7715. This issue details how
selects with a blank disabled option skip to the second option. We filed a bug
with Firefox for the problematic behavior the reverted commit addresses
https://bugzilla.mozilla.org/show_bug.cgi?id=1039047, and alternate Angular fixes are being
investigated.

Closes #7715 #7855
test(select): add test against updating selected property on digest with no change event

Commit dc149de9364c66b988f169f67cad39577ba43434 was reverted to fix regressions #7715 and #7855.
This commit introduced this test case and a corresponding fix for preventing the update of the
selected property of an option element on a digest with no change event. Although the previous fix
introduced regressions, the test covers a valid issue and should be included.
test(select): add test cases for selects with blank disabled options

An earlier commit dc149de9364c66b988f169f67cad39577ba43434 caused an error where the first option of
a select would be skipped over if it had a blank disabled value. These tests demonstrate that with
that commit in place, blank disabled options are skipped in a select. When the commit is reverted,
the correct behavior is seen that the blank disabled option is still selected in both selects
marked with required and those that have optional choices.

Relates to #7715
test(select): add test of updating the model because of ng-change

A regression #7855 was introduced by
https://github.com/angular/angular.js/commit/dc149de9364c66b988f169f67cad39577ba43434
This test ensures that reverting that commit fixes this regression.
In the regression, changes to a bound model in ng-change were not propagated back to the view.

Test for #7855
test(select): add extra expectations and comments for clarity
fix(select): do not update selected property of an option element on digest with no change event

The `render()` method was being invoked on every turn of the digest cycle,
which was inadvertently updating the DOM even when a `change` event had
not been triggered.

This change only calls the `render()` method when `ctrl.$render()` is called,
as part of the NgModelController` lifecycle and when the `modelValue` has
significantly changed.

Closes #8221
Closes #7715