simpleperf: show unwinding result in report-sample cmd.

1. Rename report_sample.proto to cmd_report_sample.proto.
2. Add unwinding_result field in cmd_report_sample.proto.
3. In report-sample cmd, show unwinding result for not
complete callchains when UnwindingResultRecord is available.

Bug: 181075274
Test: run simpleperf_unit_test

Change-Id: I870441da0135742cd41dfa860be815b19007d67a
6 files changed