adapt to array changes in julia nightly

[benlorenz]

This needs JuliaInterop/libcxxwrap-julia#137 which is not released yet.
Also requires some parts of JuliaLang/julia#52248 (depending on how this gets merged the #if can be removed again).

I removed an unused Int32 case from jl_array_to_intvec, this is only used with an explicit Int64 vector anyway.

Locally (on Linux) this works fine with julia 1.6.7, 1.9.4 and nightly with my julia PR and a custom libcxxwrap + cxxwrap.

Note that this branch was based on 0.19 instead of the latest master to allow testing with Oscar. rebased on master.

[fingolfin]

@benlorenz is this ready now? It would be good to restore compat with Julia nightly (even if we remove parts of this PR again later, once/if Julia merges your PR...)

[benlorenz]

At least some parts of the julia PR are required for this to work. Currently only a function for creating 1-dimensional arrays is exported (jl_alloc_array_1d). The _2d and _3d variants were removed and replaced with _nd, but that is not exported. The PR adds the missing export for _nd and re-adds the _2d and _3d helpers.

When I wrote and tested the code here I just added the _nd export to julia and thus needed the #if block for compatibility. If the 2d and 3d version are merged as well we can remove the #if and revert to the old code.

[benlorenz]

This does seem to work for nightly now, to build the jll we still need JuliaPackaging/Yggdrasil#7757.

[benlorenz]

I think this can be merged now and then we can create a new libsingular_julia_jll. (libjulia_jll is done)