[mlir][gpu] Refactor GpuOpsToROCDLOps pass interface (NFC) (#157402)
This PR deletes the `createLowerGpuOpsToROCDLOpsPass` constructor from
the .td file, making the `createConvertGpuOpsToROCDLOps` pass available
to users. This has the following effects:
1. `createLowerGpuOpsToROCDLOpsPass` is not available anymore. Instead,
`createConvertGpuOpsToROCDLOps` should be used. This makes the interface
consistent with ConvertGpuOpsToNVVMOps.
2. To call `createConvertGpuOpsToROCDLOps`, the options must be passed
via ConvertGpuOpsToROCDLOpsOptions. This has the side effect of
making the `allowed-dialects` option available, which was not accessible
via C++ before.