Reapply #9841: Migrate elementwise_util callers to the variants with out_dtypes in template arguments (#10491)

This is necessary to take advantage of #9388, which
creates dtype-specialized implementations for the non-mixed dtype case.

Measured the size cost of this approach with
test/build_optimized_size_test.sh . It does cost us some size:

```
Before:
ExecuTorch with no ops binary size, unstripped:
-rwxr-xr-x  1 swolchok  staff  153928 Apr 25 12:51 cmake-out/test/size_test
ExecuTorch with portable ops binary size, unstripped:
-rwxr-xr-x  1 swolchok  staff  1796928 Apr 25 12:51 cmake-out/test/size_test_all_ops
ExecuTorch with optimized ops binary size, unstripped:
-rwxr-xr-x  1 swolchok  staff  5605176 Apr 25 12:51 cmake-out/test/size_test_all_optimized_ops
(.venv) swolchok@swolchok-mac ~/src/executorch> size cmake-out/test/size_test*
__TEXT	__DATA	__OBJC	others	dec	hex
81920	81920	0	4295049216	4295213056	10003c000	cmake-out/test/size_test
1310720	81920	0	4295458816	4296851456	1001cc000	cmake-out/test/size_test_all_ops
4358144	98304	0	4296212480	4300668928	100570000	cmake-out/test/size_test_all_optimized_ops

After:
ExecuTorch with no ops binary size, unstripped:
-rwxr-xr-x  1 swolchok  staff  153928 Apr 25 12:57 cmake-out/test/size_test
ExecuTorch with portable ops binary size, unstripped:
-rwxr-xr-x  1 swolchok  staff  1889792 Apr 25 12:57 cmake-out/test/size_test_all_ops
ExecuTorch with optimized ops binary size, unstripped:
-rwxr-xr-x  1 swolchok  staff  5799704 Apr 25 12:57 cmake-out/test/size_test_all_optimized_ops
(.venv) swolchok@swolchok-mac ~/src/executorch> size cmake-out/test/size_test*
__TEXT	__DATA	__OBJC	others	dec	hex
81920	81920	0	4295049216	4295213056	10003c000	cmake-out/test/size_test
1376256	81920	0	4295491584	4296949760	1001e4000	cmake-out/test/size_test_all_ops
4423680	98304	0	4296327168	4300849152	10059c000	cmake-out/test/size_test_all_optimized_ops
```

However, on an absolute basis, size is still below where we are at two
PRs ago, which was:

```
ExecuTorch with no ops binary size, unstripped:
-rwxr-xr-x  1 swolchok  staff  153928 Apr 25 12:24 cmake-out/test/size_test
ExecuTorch with portable ops binary size, unstripped:
-rwxr-xr-x  1 swolchok  staff  2150960 Apr 25 12:24 cmake-out/test/size_test_all_ops
ExecuTorch with optimized ops binary size, unstripped:
-rwxr-xr-x  1 swolchok  staff  5887368 Apr 25 12:24 cmake-out/test/size_test_all_optimized_ops
(.venv) swolchok@swolchok-mac ~/src/executorch> size cmake-out/test/size_test*
__TEXT	__DATA	__OBJC	others	dec	hex
81920	81920	0	4295049216	4295213056	10003c000	cmake-out/test/size_test
1474560	81920	0	4295655424	4297211904	100224000	cmake-out/test/size_test_all_ops
4489216	98304	0	4296359936	4300947456	1005b4000	cmake-out/test/size_test_all_optimized_ops
```