[Triton] Add minimal matmul example (no auto tuning)

[ezhulenev]

1. Take one config from: https://github.com/openai/triton/blob/main/python/triton/ops/matmul.py
2. Trace it to Triton IR
3. Add end-to-end test

This will verify that everything works end-to-end:

1. num-warps and stages propagated to compiler
2. block dimensions are correctly computed
3. shared memory works