Add MAPI definitions for Message-ID and In-Reply-To

[JanSkalny]

Summary

Add support for reading and exporting the Internet Message-ID and In-Reply-To MAPI properties.

Changes

• Define LIBPFF_ENTRY_TYPE_INTERNET_MESSAGE_ID and LIBPFF_ENTRY_TYPE_IN_REPLY_TO_ID
• Add UTF-8 and UTF-16 convenience accessor macros
• Include Message-ID and In-Reply-To in pffexport message header output

[joachimmetz]

Thanks for the proposed changes, you might need to rebase with HEAD given you submitted the PR while I was making some changes.

I'll take a close look as soon as time permits

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 27.25%. Comparing base (9c5994a) to head (8a96976).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #159      +/-   ##
==========================================
- Coverage   27.26%   27.25%   -0.02%     
==========================================
  Files          63       63              
  Lines       20591    20530      -61     
  Branches     4975     4975              
==========================================
- Hits         5615     5596      -19     
+ Misses      13242    13200      -42     
  Partials     1734     1734              

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[JanSkalny]

Rebased. Thanks for a quick response. :)