Add IntegralsArblibExt

[lxvm]

This pr adds an extension for the recently-released Arblib.jl package (v1) with high-precision integration routines for holomorphic functions. Although the package is somewhat limited (i.e. no vector integrands or batching) I think it would be interesting to have alongside other algorithms.

I am not a user of Arblib.jl so I may have made a mistake in the implementation regarding the handling of the special number types in the package. In particular, the result type is a number containing the error estimate, instead of the integral and error estimate being separate like other Integrals.jl algorithms

[ChrisRackauckas]

Wow I didn't know this existed, that's really cool. Nice addition.

[ChrisRackauckas]

In particular, the result type is a number containing the error estimate, instead of the integral and error estimate being separate like other Integrals.jl algorithms

I do wonder if we should split it. But the Arb type generally has the radius as part of it, so it would be weird to not return a valid Arb. Maybe an improvement would be to just define the resid based off of the radius part anyways as a nicety to users, but keep the return val intact. Since that wouldn't be a breaking change I just merged this anyways, but it might be good to get an issue or follow up PR on that.

[lxvm]

Sure, extracting the radius as the error estimate makes sense, but from what I could test, the only methods that worked were abs_ubound and abs_lbound. I suppose that max(abs(abs(midpoint(ball)) - abs_ubound(ball)), abs(abs(midpoint(ball)) - abs_lbound(ball))) would give the radius