Floss: Add struct to record mSBC packets' status

So that we'll be able to dump the struct to know how many recent mSBC
packets are well received or lost.

Bug: 272101425
Tag: #floss
Test: atest --host net_test_stack_btm --no-bazel-mode
Change-Id: I2cdac93710ec04232d1715dd918a826164e1bb02