Move compute test utils to a different folder

[GraDKh]

TL;DR

Move compute_test_utils crate into the compute directory as a subdirectory.

What changed?

• Relocated the compute_test_utils crate from the top-level crates directory into a subdirectory of the compute crate
• Updated the path references in Cargo.toml files across multiple crates:
  • crates/compute/Cargo.toml
  • crates/core/Cargo.toml
  • crates/fast_compute/Cargo.toml
• Adjusted dependency paths in the test utils' Cargo.toml to reflect the new location

How to test?

• Run the test suite to ensure all tests still pass
• Verify that the build process completes successfully
• Check that imports and dependencies resolve correctly in the affected crates

Why make this change?

This change improves the project organization by placing test utilities closer to the code they're designed to test. Since these utilities are specifically for testing the compute functionality, it makes logical sense to nest them within the compute crate rather than keeping them as a separate top-level crate.

[GraDKh]

• Extract macro to instantiate ring switch tests #785
• Add a macro to instantiate bivariate_sumcheck tests #783
• Introduce macros to instantiate compute layer test #782
• Add core_test_utils crate and move core tests there #781
• Move compute test utils to a different folder #780 👈 (View in Graphite)
• main

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