Support idxs in interpolation

[avik-pal]

Fixes SciML/DiffEqDocs.jl#732

[github-actions]

Benchmark Results

	master	3959f06...	master/3959f06d9cc6ed...
Simple Pendulum/IIP/MultipleShooting(10, Tsit5; grid_coarsening = false)	1.31 ± 0.061 ms	1.29 ± 0.055 ms	1.02
Simple Pendulum/IIP/MultipleShooting(10, Tsit5; grid_coarsening = true)	2.58 ± 0.1 ms	2.55 ± 0.098 ms	1.01
Simple Pendulum/IIP/MultipleShooting(100, Tsit5; grid_coarsening = false)	29.8 ± 0.48 ms	29.4 ± 0.49 ms	1.01
Simple Pendulum/IIP/MultipleShooting(100, Tsit5; grid_coarsening = true)	0.134 ± 0.002 s	0.131 ± 0.0016 s	1.02
Simple Pendulum/IIP/Shooting(Tsit5())	0.178 ± 0.004 ms	0.178 ± 0.0032 ms	1
Simple Pendulum/OOP/MultipleShooting(10, Tsit5; grid_coarsening = false)	3.48 ± 0.31 ms	3.44 ± 0.31 ms	1.01
Simple Pendulum/OOP/MultipleShooting(10, Tsit5; grid_coarsening = true)	6.52 ± 3 ms	6.3 ± 2.6 ms	1.03
Simple Pendulum/OOP/MultipleShooting(100, Tsit5; grid_coarsening = false)	0.0867 ± 0.011 s	0.085 ± 0.0086 s	1.02
Simple Pendulum/OOP/MultipleShooting(100, Tsit5; grid_coarsening = true)	0.377 ± 0.0047 s	0.376 ± 0.0061 s	1
Simple Pendulum/OOP/Shooting(Tsit5())	0.745 ± 0.027 ms	0.747 ± 0.024 ms	0.997
time_to_load	5.73 ± 0.023 s	5.71 ± 0.075 s	1

Benchmark Plots

A plot of the benchmark results have been uploaded as an artifact to the workflow run for this PR.
Go to "Actions"->"Benchmark a pull request"->[the most recent run]->"Artifacts" (at the bottom).