Add abstraction to cleanly input arrays and slices to black box funcs

[vezenovm]

Problem

From PR #2435 description:
The internal structure of slices in SSA was changed in #2347. Slices and arrays are polymorphic over each other, thus slices can be passed to functions that accept arrays with a generic size (ex. fn foo(input: [Field; N]). The slice structure is handled in SSA, but in ACIR gen we setup the inputs to for the black box calls manually. As the slice length always precedes the slice contents, without changes to call_black_box in acir gen, the slice length was being passed to the bb funcs rather than the contents of the slice.

Happy Case

PR #2435 introduced a quick solution to get this fixed, but we should introduce a clean abstraction for differentiating between arrays and slices. Slice inputs to black box function should be handled in a generalizable way that reduces the surface area for bugs.

Alternatives Considered

Keep the manual check for every potential slice input. This can lead to potential bugs if the implementer of a new black box func that accepts arrays generic over their size forgets to handle slices.

Additional Context

N/A

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