feat: use OSS ICICLE for GPU acceleration (version v3.2.2)

[ivokub]

Description

Link against the OSS version of ICICLE. Also update some changed APIs

Type of change

• New feature (non-breaking change which adds functionality)

How has this been tested?

Tested an example ECDSA circuit locally. It is not committed as we don't have GPU accelerated CI anyway and it requires a setup.

Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• I did not modify files generated from templates
• golangci-lint does not output errors locally
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

Pull Request Overview

This PR updates the project to link against the OSS version of ICICLE (v3.2.2) for GPU acceleration. Key changes include updating the import paths from icicle/v3 to icicle-gnark/v3, modifying the device warmup logic to create and use a stream, and updating documentation links accordingly.

Reviewed Changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
backend/groth16/bn254/icicle/icicle.go	Updated ICICLE import paths to the new OSS repo
backend/groth16/bn254/icicle/device.go	Modified device warmup logic to incorporate stream creation
backend/backend.go	Updated documentation links to reflect new repo
README.md	Revised repository link for prerequisites
backend/groth16/bn254/icicle/provingkey.go	Updated core import path to use icicle-gnark

Files not reviewed (1)

• go.mod: Language not supported