Removes leftover code from citra that isn't needed.

There may be many CodeSets per Process, so it's wasteful and overcomplicated to store the program id in each of them.

# Conflicts:
#	src/core/CMakeLists.txt
#	src/core/arm/dynarmic/arm_dynarmic.cpp
#	src/core/arm/dyncom/arm_dyncom.cpp
#	src/core/hle/kernel/process.cpp
#	src/core/hle/kernel/thread.cpp
#	src/core/hle/kernel/thread.h
#	src/core/hle/kernel/vm_manager.cpp
#	src/core/loader/3dsx.cpp
#	src/core/loader/elf.cpp
#	src/core/loader/ncch.cpp
#	src/core/memory.cpp
#	src/core/memory.h
#	src/core/memory_setup.h