TRIBS-134 Re-do Aac search using new search_text field

For AAC, instead of concatenating metadata and text fields, store all the concatenated data in a separate field called search_text. There's a before_save hook on the model, which updates this field on changes to other fields. Similar hooks will need to be added to the associated models.

If this works well, will extend it to all other models, possibly in a separate single table containing search text for all of them to allow cross-tribunals search in the future.

Bunch of other fixes on the landing page display.