Implement a new section to attach LAST_KMSG to incident report

This section simply gzip a large file and stores result in GZippedFileProto

This greatly improves the size, before gzip, the last kmsg size ~500KB,
after gzip the proto size is ~60KB.

Bug: 73354384
Test: atest incidentd_test and manual on device test
Change-Id: I9bfc2cf07384487671edbffb5f0bd8495608fea6