fix(skyrim-platform): update SkyrimPlatform.cpp

[Pospelove]

[!IMPORTANT] Adds scriptSrc to Msg struct in SkyrimPlatform.cpp for script source handling during plugin loading.

• Behavior:
  • Adds scriptSrc member to Msg struct in SkyrimPlatform.cpp to handle script source during plugin loading.
  • Updates sizeof(Msg) assertion from 24 to 32 to reflect new struct size.
• Misc:
  • Updates msg.scriptSrc assignment in PatchPluginFile() to use scriptSrc.data().

^{This description was created by for 78e89e48efbc88e754a8639c3c3bba5467aa20dc. It will automatically update as commits are pushed.}