Inconsistency in Interface

[sathvikbhagavan]

All methods can take in a Vector of numbers, few methods take in Matrices, Vector of Vectors etc. We should have a consistent interface for all or document this API, reason for it etc.

Methods which can take in Matrices:

1. LinearInterpolation - https://github.com/SciML/DataInterpolations.jl/blob/master/src/interpolation_methods.jl#L27C26-L27C45
2. QuadraticInterpolation - https://github.com/SciML/DataInterpolations.jl/blob/master/src/interpolation_methods.jl#L50C26-L50C48
3. LagrangeInterpolation - https://github.com/SciML/DataInterpolations.jl/blob/master/src/interpolation_methods.jl#L88C26-L88C47
4. ConstantInterpolation - https://github.com/SciML/DataInterpolations.jl/blob/master/src/interpolation_methods.jl#L146C26-L146C47

So, AkimaInterpolation, QuadraticSpline, CubicSpline, BSplineInterpolation, BSplineApprox does not work with Matrices

Methods which does not work with Vector of Vectors:

AkimaInterpolation, BSplineInterpolation, BSplineApprox