keep the input type in reimZeroFilling

when the input of reimZeroFilling is [DataReIm](https://github.com/mljs/spectra-processing/blob/bfab310b54d96ff11ee93fa1465f3aa5534aa5e3/src/types/DataReIm.ts#L3-L10)`<Float64Array>` the returning data type is DataReIm<DoubleArray>. So in order to avoid the use of `xEnsureFloat64` the use of generic type would helps in some cases where data is restricted to Float64Array.