Draft: Pass buffers size along with the associated buffer

This is an updated version of !25 with some updates:

• builds on top of libdvdread 7.0.0 containing libdvdread!31
• use size_t and size_t* for the buffer sizes
• don't export packed structure definitions
• rebased on current libdvdnav master
• updated the Changelog with the API changes

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original Merge Request info:

This is a follow up to libdvdread!22 and aims at preventing out of bounds read

This has been minimally tested. I'm not entirely sure that this change is required, or if it should be this invasive as it spans across 2 projects, not including the applications using libdvd*