[mlir][sparse] Improving ExecutionEngine/SparseTensorUtils.h

[mlir][sparse] Improving ExecutionEngine/SparseTensorUtils.h

This change makes the public API of SparseTensorUtils.cpp explicit, whereas before the publicity of these functions was only implicit.  Implicit publicity is sufficient for mlir-opt to generate calls to these functions, but it's not enough to enable C/C++ code to call them directly in the usual way (i.e., without going through codegen).  Thus, leaving the publicity implicit prevents development of other tools (e.g., microbenchmarks).

In addition this change also marks the functions MLIR_CRUNNERUTILS_EXPORT, which is required by the JIT under certain configurations (albeit not for anything in our test suite).

Reviewed By: aartbik

Differential Revision: https://reviews.llvm.org/D126105