More DRY e() helper & consistent html entities in HtmlBuilder

See Issue #4782.

The changes away from `e()` are to prevent failing tests. With `e()` depending on `app('html')`, tests for the html/form builder classes and the blade view compiler class will complain that `App::make` doesn't exist. `HtmlBuilder` and `FormBuilder` fix is easy, because `HtmlBuilder::entities()` is readily available (`FormBuilder::$html` is an instance of `HtmlBuilder`). For escapes compiled by blade, the `HtmlBuilder` can be retrieved with `$app['html']` (which required editing some tests to change expectations to not include the `e()` helper). 
This actually enforce `e()` to be available only if html service location is available. Should check if the the service location is bound