ISTWCMS-6380 Add multiTypePromoteTest() to check multi type list promote display
Added multiTypePromoteTest which checks that only promoted blogs, events, news, and opportunities are displayed in multi-type list content blocks when only promoted items are supposed to appear. When all items are supposed to appear, it checks that they do.
Code adds 2 blog posts, events, news, and opportunities web pages each, with one promoted to the front and the other not. 2 multi-type list blocks are created: one which features only promoted items and (after the prev is deleted) one which features all. All pages are deleted at the end of the function.