Provide generic Time Series datatype

[bertini97]

Is your feature request related to a problem? Please describe.

I need an object that stores a vector of arrays and the corresponding times, in a way that it can be indexed as a matrix. This package, and in general DiffEqArray is perfect. However, it's missing interpolation, and it seems tied to the DiffEq packages.

Describe the solution you’d like

Having a type AbstractTimeSeries, for example, that:

• Represents all object of this kind
• Implements methods such us interpolation (e.g. ats(t), ats(out, t), etc). these methods can be further specialized for ODEs, or when the derivative is known
• Can be indexed as a matrix, etc.
• Has a concrete type TimeSeries that can be constructed just from u, t

I think SciML has such abstract type, but up to my knowledge it's not interpolable nor constructable.

Additional context

Packages like ReservoirComputing.jl could make use of a type like this to store a solution, which is not necessary an ODE.

If what I need is already in place, please inform me and I'll close this right away.