Add framework stats for the Context Hub service

Adding common framework stats that are present in the AOSP
HAL to the Context Hub service so all platforms have the
debug information available

Example output:

=================== EVENTS ====================
Nanoapp Loads:
09/06 16:56:30.075: NanoappLoadEvent[hubId = 0, appId = 0x476f6f6754fffffc, appVersion = 0, appSize = 15232 bytes, success = true]

Nanoapp Unloads:
09/06 16:56:27.243: NanoappUnloadEvent[hubId = 0, appId = 0x476f6f676c00100b, success = true]

Messages from Nanoapps:
09/06 16:56:01.399: NanoappMessageEvent[hubId = 0, NanoAppMessage[type = 1025, length = 10 bytes, broadcast, nanoapp = 0x476f6f676c001004](data = 0x01000006 00003000 0801), success = true]

Messages to Nanoapps:
09/06 16:56:03.684: NanoappMessageEvent[hubId = 0, NanoAppMessage[type = 0, length = 18 bytes, unicast, nanoapp = 0x476f6f676c001004](data = 0x1100000E 00003100 08011001 18012001 ...), success = true]

Context Hub Restarts:
09/06 16:56:53.109: ContextHubRestartEvent[hubId = 0]

Bug: 217576459
Test: m && ./vendor/google/tools/flashall
Test: gts-tradefed run everything --skip-system-status-check com.android.compatibility.common.tradefed.targetprep.NetworkConnectivityChecker --module GtsGmscoreHostTestCases --primary-abi-only --test com.google.android.gts.locationcontext.LocationContextHostTest#testContextHubBusyStartupNanoAppTest
Test: adb shell 'echo mem dump 0 > /dev/acd-debug'
Test: adb shell dumpsys contexthub
Change-Id: I3bd879e3069c187125f9a6b001e56e064b0613f7