The name based mime type is inaccurate, so it should not be used to
decide if a file should be indexed. In case a specific extension should
be skipped this can still be done accurately by the name based filters,
e.g. instead of "image/png" "*.png" can be used, or the whole directory
can be excluded.

This inaccuracy is also confusing for the user, as a file without
extension will be added to the index, but adding an extension removes
the file from the index. The file extension may also be ambiguous.

This also matches the current list of excluded mime types, which are
source files for various languages. These blow up the full text index
and thus should be excluded (by default), but just adding the file names
increases the index size only marginally.

The 'inability' to find files is a recurring user complaint.

CCBUG: 422085

Depends on D28932