[BE] Get rid of code duplication (#110619)
Replace `dispatch_to_CDouble`, `dispatch_to_CLong` and `dispatch_to_CComplexDouble` with `dispatch_to<T>` template
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### <samp>🤖 Generated by Copilot at c3d9d01</samp>
> _Sing, O Muse, of the clever coder who devised_
> _A wondrous template function, `dispatch_to<T>`, that could_
> _Handle with ease the various scalar types that vexed_
> _The previous code, which was verbose and dull as wood._
Pull Request resolved: https://github.com/pytorch/pytorch/pull/110619
Approved by: https://github.com/soulitzer, https://github.com/albanD
ghstack dependencies: #110618
