[triton-mlir][BACKEND] Support masked load/store (#657)

This PR does

- fix some bugs to support masked load/store,
- refine frontend, and support the `and` and `or` syntax in mask(by
extending the BoolOp in python ast.visitor), e.g. `tl.store(...,
mask=offset<n and other_conditions)`,
- add `arith.cmpI` and `arith.cmpF` op conversion in backend(required by
mask),
- add more test cases in vecadd.

python/tests/test_gemm.py

@@ -1,6 +1,6 @@
 import pytest
 import torch
-from torch.testing import assert_allclose
+from torch.testing import assert_close
 
 import triton
 import triton.language as tl
@@ -49,4 +49,4 @@ def test_gemm_impl(SIZE_M, SIZE_N, SIZE_K, NUM_WARPS):
                         num_warps=NUM_WARPS)
     golden = torch.matmul(a, b)
     torch.set_printoptions(profile="full")
-    assert_allclose(c, golden, rtol=1e-3, atol=1e-3)
+    assert_close(c, golden, rtol=1e-3, atol=1e-3, check_dtype=False)