jni: OomConnection: Update for libmemevents API changes

The MemEventListener now requires to pass a `MemEventClient` for it to map the BPF program, and ring-buffer, to the corresponding client.
Other API changes include the replacement of `getOomEvents()` to
`getMemEvents()`, and the return value tyoe of `listen()`.

Test: m
Test: Trigger OOM kill and verify `noteAppKill()` is called with the
matching OOM victim data
Bug: 315560026
Change-Id: Ia8b89110ac985417fc51ca3ef94191b116ca3658
Signed-off-by: Carlos Galo <carlosgalo@google.com>
Merged-In: Ia8b89110ac985417fc51ca3ef94191b116ca3658