LLVM IR lowering: support integer division and remainder operations

These operations trivially map to LLVM IR counterparts for operands of scalar
and (one-dimensional) vector type.  Multi-dimensional vector and tensor type
operands would fail type conversion before the operation conversion takes
place.  Add tests for scalar and vector cases.  Also add a test for vector
`select` instruction for consistency with other tests.

PiperOrigin-RevId: 228077564