feat: Dynamic index for slice insert and remove

[vezenovm]

Description

Problem*

Resolves #2462

Summary*

This PR simply builds upon #3617 by including some tests that use a dynamic index on SliceInsert and SliceRemove.

Additional Context

Documentation*

Check one:

• No documentation needed.
• Documentation included in this PR.
• [Exceptional Case] Documentation to be submitted in a separate PR.

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[github-actions]

Changes to circuit sizes

Generated at commit: c4d3bcb2a9d203c22d64a8f53a95b02c07502806, compared to commit: 7baaa2e12bd5ac0238cd4ab4e4b41ac557adefe0

🧾 Summary (10% most significant diffs)

Program	ACIR opcodes (+/-)	%	Circuit size (+/-)	%
slice_struct_field	+6,798 ❌	+24.20%	+15,494 ❌	+16.87%
slice_dynamic_index	+25 ❌	+0.88%	+32 ❌	+0.28%

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Full diff report 👇

Program	ACIR opcodes (+/-)	%	Circuit size (+/-)	%
slice_struct_field	34,892 (+6,798)	+24.20%	107,356 (+15,494)	+16.87%
slice_dynamic_index	2,860 (+25)	+0.88%	11,514 (+32)	+0.28%

[vezenovm]

@jfecher This PR builds upon #3617 so I was thinking to merge this PR once the parent is in master. Although this is mainly test changes so if you are fine with it I can squash into the parent whenever.

[TomAFrench]

If it's just adding tests for a feature added in the other PR I think we can merge it into there.