Increases width of defaultsort and page redirect fields in options dialog

This patch increases the width of the defaultsort field, a problem
identified in bug 51012. It does this by adding a custom class in
/modules/ve-mw/ui/pages/ve.ui.MWCategoriesPage.js called
.ve-ui-mwCategoriesPage-defaultsort and then applying the style in
modules/ve-mw/ui/styles/ve.ui.Page.css.

The patch also increases the width of a field that was not addressed
in the bug report, the page redirect field in the page settings
page in the options dialog. This was done because, like the
defaultsort field, this field takes as input page titles, which
can sometimes be long. This was done by adding a style to
modules/ve-mw/ui/styles/ve.ui.MWWidget using the
.ve-ui-mwTitleInputWidget class, a class which had been added
to the input field but didn't have any styles associated with it
until this commit.

In both fields, the width has been set to 30em.

Bug: 51012
Change-Id: Ic24f0d20256a5d64075f9d2850215a03b8c8ae66
Merge "Increases width of defaultsort and page redirect fields in options dialog"