ANDROID: mm: Add slab object iteration helper

Add and export a helper function which iterates through all the
kmem_cache objects.

Also export get_track() and make struct track available to outside
modules that want the ability to collect slab tracking data using the
newly added function.

Bug: 394900912
Bug: 444616776
Change-Id: I8b920f6bd770c5386ae5a702b8e04107d5663504
Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
Signed-off-by: Ketan Kishore <ketan.kishore@oss.qualcomm.com>