Move Fft caching into the GpuExecutor, the only StreamExecutor that does them.
Move Fft caching into the GpuExecutor, the only StreamExecutor that does them.

FUTURE_COPYBARA_INTEGRATE_REVIEW=https://github.com/openxla/xla/pull/11182 from Tixxx:tixxx/optimize_cp a2fbc7d29d3d8106753f36e2a477e0889da6cb58
