Upgrade Rust to 1.76.0-nightly

[jgreat]

Highlights

• Add retry config for flaky CI tests.
• Update rust-version in Cargo.toml files.
• update rocket to 0.5.1 and remove old clippy allow
• Add clippy allow for #![feature(core_intrinsics)] in attest/core/src/lib.rs - I think we're using this here due to setting #![no_std] and needing the abs() function/method for f64. This is almost dead IAS code, so didn't think it was worth spending time and testing refactoring.

clippy::blocks-in-conditions - remove functions/closures that are in-line with match statements. I'm happy to change any of the variable names I made up when moving the closures.

• consensus/enclave/trusted/src/lib.rs
• fog/ledger/enclave/trusted/src/lib.rs
• fog/ingest/enclave/trusted/src/lib.rs
• fog/view/enclave/trusted/src/lib.rs
• ledger/sync/src/ledger_sync/ledger_sync_service.rs

clippy::implied_bounds_in_impls

• consensus/enclave/impl/src/constant_time_token_map.rs

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