[mlir][complex] Allow integer element types in `complex.constant` ops (#74564)

The op used to support only float element types. This was inconsistent
with `ConstantOp::isBuildableWith`, which allows integer element types.
The complex type allows any float/integer element type.

Note: The other complex dialect ops do not support non-float element
types yet. The main purpose of this change to fix
`Tensor/canonicalize.mlir`, which is currently failing when verifying
the IR after each pattern application (#74270).

```
within split at mlir/test/Dialect/Tensor/canonicalize.mlir:231 offset :8:15: error: 'complex.constant' op result #0 must be complex type with floating-point elements, but got 'complex<i32>'
  %complex1 = tensor.extract %c1[] : tensor<complex<i32>>
              ^
within split at mlir/test/Dialect/Tensor/canonicalize.mlir:231 offset :8:15: note: see current operation: %0 = "complex.constant"() <{value = [1 : i32, 2 : i32]}> : () -> complex<i32>
"func.func"() <{function_type = () ->...