GitLab

**Description**
Unify metric names of benchmarks.

**Description**
Revise the all the term `onnx` to `onnxruntime`.

**Description**
Change the field name `reduce` to `reduce_op`.

Add ReduceType description into benchmarks doc.

**Description**
Add Executor and Benchmarks design doc

**Major Revision**
- Add Executor design doc
- Add Benchmarks design doc