Add APIs in IIpMemoryStore.aidl to retrieve or store a specific network event. am: 6dece56497 am: 3ef8c95c66

Original change: https://android-review.googlesource.com/c/platform/packages/modules/NetworkStack/+/3244200

Change-Id: I8fc48591c904cf6e06ce14c5eb6ef6455fa459ce
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>