[Rust] Eliminate indirection of ZST allocations

[asfimport]

Currently, no matter what any array construction without data creates 0 sized layouts and passes itself to Rust's allocator API, thus OS then comes back to the program and does the job.

This issue is two-fold:

• First, this creates indirection and UB in a sense.

• Second, degrades the performance for the merging simd, merging arrays, constructing arrays etc. and intermediate arrays when doing ops. over them.

  The solution would be:

• Having UB solved without a performance downside.

• Improve the performance

Reporter: Mahmut Bulut / @vertexclique
Assignee: Mahmut Bulut / @vertexclique

PRs and other links:

• GitHub Pull Request #7061

_{Note: This issue was originally created as ARROW-8629. Please see the migration documentation for further details.}

[asfimport]

Andy Grove / @andygrove:
Issue resolved by pull request 7061
#7061