Shuffle files around, use TableGen to register passes, and introduce a `mlir-hlo-opt.cpp` file to hold the main entry point of the -opt tool and stop relying on static registration for dialect/passes. PiperOrigin-RevId: 323674455
PiperOrigin-RevId: 320320140
This is part of the current refactoring of the HLO related dialect. `xla_hlo` will be reintroduced in a new form later. PiperOrigin-RevId: 319916753