Use schema string specification in derivatives.yaml. (#20916)
Summary:
For consistency, derivatives.yaml now uses the same schema specification as native_functions.yaml.
Note that there are some small downsides, e.g. changing the default values or return parameter names in native_functions.yaml also now requires updating derivatives.yaml as well. But this has a few nice properties:
1) Able to copy-paste definitions from native_functions to derivatives.
2) Makes it impossible to write derivatives for operators without schemas (e.g. old TH operators).
3) Moves us closer to the ideal situation of co-locating forward and backwards declarations.
Note that this doesn't change any generated code; in particular, this has the same behavior of mapping in-place and out-of-place definitions together.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/20916
Differential Revision: D15497800
Pulled By: gchanan
fbshipit-source-id: baee5caf56b675ce78dda4aaf6ce6a34575a6432
