Arvados

Since searching "text" columns is too slow, we do not want to include text columns in searchable_columns.

However, this would mean the collections search for file names will not be comprehensive enough without searching in "manifest_text" column.

Hence we want to add a new column of type string with file names only, truncated to the allowed size.

What we need:

- Add a file_names column to collections data model (of size 64K or so)

- Use this column when searching for "any" instead of manifest_test column

- Remove text columns from searchable_columns