Refactor views_ui_rearrange_form to remove theme function for table render

We currently have a theme_views_ui_rearrange_form function that renders the form build to be a table. Nowadays we can just do this natively using the form/render api in our form callback.

There is a related issue, #1921774: Javascript on reorder modal form tables is missing., meaning the javascript for tabledrag is not included when first opening the modal. This issue can still carry on without that though.

I have also created #1929070: Refactor views_ui_rearrange_filter_form to remove theme function for table rendering for the filter rearrange form.