Renames nanoapp instance IDs to handles in ContextHubService

Use handles to refer to nanoapp instances at the service to be
consistent with the terminology at NanoAppInstanceInfo, and to
reduce confusion with other instance IDs (e.g. ones maintained
in the CHRE implementation).

Bug: 67734082
Test: None
Change-Id: Iab60b4df20383907668824ac95c3f5a1a559ee6b
2 files changed