Powerpoint and Excel mimetypes missing "sub-class-of" information

SUMMARY:

The freedesktop.org.xml mimetype definitions need extra "sub-class-of" links for Microsoft formats
such as ".ppt" and ".xls"

The definition for ".doc" includes:

    <mime-type type="application/msword">
      ...
      <sub-class-of type="application/x-ole-storage"/>
      ...

which allows KDE free-text indexing (by baloo) to determine a file extractor. However the entries
for ".ppt" and ".xls" do not include this subclass information, apparently Access files as well
(although I'm not able to test this)

Without the "sub-class-of", .ppt and .xls files are considered "application/x-ole-storage" and are
not indexed.

See:
    https://bugs.kde.org/show_bug.cgi?id=438455
with the pointer to the issue:
    https://bugs.kde.org/show_bug.cgi?id=438455#c23

SOFTWARE/OS VERSIONS

Neon Testing

Plasma : 5.26.80
Frameworks : 5.101.0
Qt : 5.15.7

$ dpkg-query --show shared-mime-info
shared-mime-info        2.2-0xneon+22.04+jammy+unstable+build4

ADDITIONAL INFORMATION

The issue was originally identified on Neon Testing (above) but it also exists on Manjaro and Fedora 37

An override file with the subclass information added (for .ppt and .xls):
    https://bugs.kde.org/attachment.cgi?id=153934

Thanks to Stefan Brüns for the pointer...

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