libtimeinstate: move map format info into shared header

Switch from using timeinstate.h to a shared header in system/bpf that
provides key & value struct definitions both to libtimeinstate and to
our BPF program

Test: build libtimeinstate
Bug: 138317993
Change-Id: I302b40bd1dfa7b529888f598cf36c146400f1315
Signed-off-by: Connor O'Brien <connoro@google.com>