Missing isCorpse check at ProtocolGame::sendContainer

Before creating an issue, please ensure:

• This is a bug in the software that resides in this repository, and not a support matter (use https://otland.net/forums/support.16/ for support)
• This issue is reproducible without changes to the C++ code in this repository

Steps to reproduce (include any configuration/script required to reproduce)

1. Kill a monster
2. Open its corpse
3. Move any item to inside the corpse

Expected behaviour

Should not be possible, a red square will appear in the slot you are trying to move it to

Actual behaviour

You can add any item to monster corpses

Explanation

I don't know since when it was added, but its there on official, and I think it was done to prevent some analyzers to not contain misinformation

Related code

here is the part that need a isCorpse() check

PS

Make it configurable, but enabled by default