test(smc): add unit tests for SMC-R networking functionality

- Implement comprehensive unit tests for SMC-R networking features
- Cover various scenarios including success and failure cases
- Mock system commands and file operations for isolated testing
- Use testify/assert for test assertions
- Include tests for ensuring SMC-R support, configuring devices, and handling errors

Signed-off-by: l1b0k <libokang.lbk@alibaba-inc.com>

Author: l1b0k