Fix filename for blob extracted from an email when the name attribute is missing

Thanks to NXP-30062, images embedded in mail without content disposition are correctly extracted, but NXP-30062 does not handle the case where the name is also missing.

In this case, the blob name is set to the mail title without extension.

We could add a little trick to ExtractMessageInformationAction#getFilename to concatenate an extension from the mail part content type.

Example which is working fine

 --------------14A4C4111B6C3B40E3BED54D
Content-Type: image/png;
 name="bmkkflcpoiogbdgk.png"
Content-Transfer-Encoding: base64
Content-ID: <part1.52918F35.E0DF2FBA@xxx.com>

Example which provokes the problem

--------------14A4C4111B6C3B40E3BED54D
Content-Type: image/png
Content-Transfer-Encoding: base64
Content-ID: <part1.52918F35.E0DF2FBA@xxx.com>