Resizing preparation results

[gdalle]

As discussed with Chris R. on Slack, one of the missing pieces for OrdinaryDiffEq is the ability to resize the cache for dynamical system with growing inputs.

• Example use: https://docs.sciml.ai/DiffEqDocs/stable/features/callback_functions/#Example-3:-Growing-Cell-Population
• Relevant code: https://github.com/SciML/OrdinaryDiffEq.jl/blob/master/lib/OrdinaryDiffEqDifferentiation/src/derivative_wrappers.jl#L323-L356

Warning

Any optimized implementation for a given backend will use package internals.