Some mime types are missing

Problem

There are a number of file extensions for the Open Document Format, od?, in the configuration file "config/install/search_file_attachments.settings.yml" for which no mime types are defined in "src/MimetypeService.php", so they will not be indexed. Furthermore the file extensions pps and ppsx for MS Office slideshows, together with their mime types, are missing.

Proposed resolution

Attached are two patches to remedy these two problems, one for the configuration file (search_file_attachments.settings.yml.1.2.diff) and one for the php file with the MimetypeService (MimetypeService.php.1.2.diff).