GitLab

**Description**
Integrate monitor into Superbench.

**Major Revision**
- Initialize, start and stop monitor in SB executor.
- Parse the monitor data in SB runner and merge into benchmark results.
- Specify ReduceType for monitor metrics, such as MAX, MIN and LAST.
- Add monitor configs into config file.

**Description**
Add reduce function support for output summary.

**Major Revision**
- Add reducer class to maintain all reduce functions.
- Save reduce type of each metric into `BenchmarkResult`
- Fix UT.