chore: bump icicle to v2.8.0

[mrain]

no issue related.

This PR:

• bump icicle deps to v2.8.0
  • HostOrDeviceSlice is now a trait. Occurrences are changed to concrete types now.
  • For Bn254 curve impl
  • commit_on_gpu now assume that the input scalars are in normal form instead of montgomery form.
  • now load_poly_to_gpu has one memory copy instead of free as before
  • these are because, icicle field impl now uses u32 limbs instead of u64 limbs as in arkworks.
• add GPU stress test for memory leakage/fragmentation

This PR does not:

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Before we can merge this PR, please make sure that all the following items have been checked off. If any of the checklist items are not applicable, please leave them but write a little note why.

• [ ] Targeted PR against correct branch (main)
• [ ] Linked to GitHub issue with discussion and accepted design OR have an explanation in the PR that describes this work.
• [ ] Wrote unit tests
• [ ] Updated relevant documentation in the code
• [ ] Added relevant changelog entries to the CHANGELOG.md of touched crates.
• [ ] Re-reviewed Files changed in the GitHub PR explorer

[alxiong]

thanks @mrain for taking the initiative to upgrade our icicle dep! 👍