[springboard] Use LMResponseConsumePropertyList in IPC recieve function

[leptos-null]

LMResponseConsumePropertyList converts the given response into a property list, just like the ReceivedRelayedNotification function implements. Additionally, this cleans up both the data and request (now response in this PR) being leaked.

The LMResponseBuffer struct is the LMMessage struct with the buffer padding at the end. Due to C struct layouts, this allows them to be used interchangeably. The size check is still correct.

Edit: Here's a link to the implementation of LMResponseConsumePropertyList checked out at the current theos/headers commit

[kirb]

I’ll need to recall why I did that instead of using LMResponseConsumePropertyList, it may have been that the logic wasn’t ARC-friendly but I believe those issues were fixed. Could even just be something I forgot to clean up after debugging once many years ago…

Thanks!