feat: support AllReduce example with OpenMPI backend implementation

[Ziminli]

Summary

This PR adds support for six communication operations required by the AllReduce example (i.e., examples/all_reduce.cc), enabling InfiniCCL to perform AllReduce using an OpenMPI backend.
In addition, this PR introduces a lightweight logging module and refactors the AllReduce example to improve structure, usability, and maintainability.

Changes

• Communication Operation Support
  • add the basic OpenMPI implementation for:
    • infiniGetRank()
    • infiniGetSize()
    • infiniFinalize()
    • infiniCommInitAll()
    • infiniCommDestroy()
    • infiniAllReduce().
• Example Refactor
  • extract common utilities shared across example programs under examples/;
  • add Timer, Metrics, and Validator in examples/utils.h for simple profiling and result checking;
  • refactor example build logic to allow access to internal components (e.g., runtime), avoiding redundant boilerplate not relevant to testing.
• Logging
  • add a lightweight logging module in src/logging.h for structured information and error reporting.

Known Issues & Future Work

• The current AllReduce example has only been tested on a single node (NVIDIA environment). Multi-node and heterogeneous setups still require a complete validation.
• The logging module is temporary and will be replaced with glog in the future.
• In the current test environment, OpenMPI consistently reports the warning: mpirun has exited due to process rank <RANK#> with PID <PID#> on node <IP> exiting improperly message. This issue has been investigated but not fully resolved. It does not appear to impact functionality at this time, but should be addressed in future work.

Logs & Screenshots

cmake .. && make -j$(nproc) && mpirun -n 8 --mca mtl ^ofi --mca btl tcp,self -x UCX_NET_DEVICES=all --allow-run-as-root ./examples/all_reduce
-- No backend specified. Defaulting to WITH_OMPI=ON
-- Auto-detecting available devices...
-- Auto-detected NVIDIA environment.
-- No MetaX GPU detected
-- InfiniCCL Config: Devices [cpu, nvidia] | Backends [ompi]
-- Configuring done (2.0s)
-- Generating done (0.0s)
-- Build files have been written to: /nfs/lizimin/InfiniCCL/build
[ 20%] Generating InfiniCCL bridge and manifest files for Devices: [cpu;nvidia] Backends: [ompi]...
[ 40%] Building CXX object src/CMakeFiles/infiniccl.dir/comm_bridge.cc.o
[ 60%] Linking CXX shared library libinfiniccl.so
[ 60%] Built target infiniccl
[ 80%] Building CXX object examples/CMakeFiles/all_reduce.dir/all_reduce.cc.o
[100%] Linking CXX executable all_reduce
[100%] Built target all_reduce
[1777519993.621796] [server:4161359:0]          parser.c:2305 UCX  WARN  unused environment variable: UCX_ROOT (maybe: UCX_PROTOS?)
[1777519993.621796] [server:4161359:0]          parser.c:2305 UCX  WARN  (set UCX_WARN_UNUSED_ENV_VARS=n to suppress this warning)
[1777519993.623801] [server:4161354:0]          parser.c:2305 UCX  WARN  unused environment variable: UCX_ROOT (maybe: UCX_PROTOS?)
[1777519993.623801] [server:4161354:0]          parser.c:2305 UCX  WARN  (set UCX_WARN_UNUSED_ENV_VARS=n to suppress this warning)
[1777519993.626339] [server:4161361:0]          parser.c:2305 UCX  WARN  unused environment variable: UCX_ROOT (maybe: UCX_PROTOS?)
[1777519993.626339] [server:4161361:0]          parser.c:2305 UCX  WARN  (set UCX_WARN_UNUSED_ENV_VARS=n to suppress this warning)
[1777519993.636061] [server:4161355:0]          parser.c:2305 UCX  WARN  unused environment variable: UCX_ROOT (maybe: UCX_PROTOS?)
[1777519993.636061] [server:4161355:0]          parser.c:2305 UCX  WARN  (set UCX_WARN_UNUSED_ENV_VARS=n to suppress this warning)
[1777519993.641585] [server:4161357:0]          parser.c:2305 UCX  WARN  unused environment variable: UCX_ROOT (maybe: UCX_PROTOS?)
[1777519993.641585] [server:4161357:0]          parser.c:2305 UCX  WARN  (set UCX_WARN_UNUSED_ENV_VARS=n to suppress this warning)
[1777519993.645557] [server:4161360:0]          parser.c:2305 UCX  WARN  unused environment variable: UCX_ROOT (maybe: UCX_PROTOS?)
[1777519993.645557] [server:4161360:0]          parser.c:2305 UCX  WARN  (set UCX_WARN_UNUSED_ENV_VARS=n to suppress this warning)
[1777519993.673396] [server:4161356:0]          parser.c:2305 UCX  WARN  unused environment variable: UCX_ROOT (maybe: UCX_PROTOS?)
[1777519993.673396] [server:4161356:0]          parser.c:2305 UCX  WARN  (set UCX_WARN_UNUSED_ENV_VARS=n to suppress this warning)
[1777519993.770086] [server:4161358:0]          parser.c:2305 UCX  WARN  unused environment variable: UCX_ROOT (maybe: UCX_PROTOS?)
[1777519993.770086] [server:4161358:0]          parser.c:2305 UCX  WARN  (set UCX_WARN_UNUSED_ENV_VARS=n to suppress this warning)
[Rank 2] Host: server | GPU: nvidia  | Device 2
[Rank 6] Host: server | GPU: nvidia  | Device 6
[Rank 4] Host: server | GPU: nvidia  | Device 4
[Rank 7] Host: server | GPU: nvidia  | Device 7
[Rank 1] Host: server | GPU: nvidia  | Device 1
[Rank 3] Host: server | GPU: nvidia  | Device 3
[Rank 5] Host: server | GPU: nvidia  | Device 5
[Rank 0] Host: server | GPU: nvidia  | Device 0

=== Performing AllReduce on GPU Memory ===
Data size: 1048576 floats (4 MB)
Operation: Sum
Warm-up iterations: 2
Profile iterations: 20

=== AllReduce Results ===
Correct: YES
Expect:  36.00
Actual:  36.00
Time:           12.898 ms
Throughput:     0.53 GB/s (Bus BW)
Alg Bandwidth:  0.30 GB/s
InfiniCCL finalized.