Update Rust dependencies for turbo-persistence and turbo-tasks-backend (#90774)
### What?
Updates outdated Rust dependencies used by `turbo-persistence` and
`turbo-tasks-backend` crates.
### Why?
Keep dependencies current to benefit from bug fixes, performance
improvements, and security patches.
### How?
Each dependency was updated in a separate commit. All crates were
verified to compile and tests pass.
**Direct dependency updates:**
- `lzzzz` 1.1.0 → 2.0.0 (moved to workspace dependency, used by both
crates)
- `arc-swap` 1.7.1 → 1.8.2 (turbo-tasks-backend)
**Workspace dependency updates:**
- `bitfield` 0.18 → 0.19
- `either` 1.9 → 1.15
- `indexmap` 2.7 → 2.13
- `once_cell` 1.17 → 1.21
- `rand` 0.9 → 0.10 (required API migration: `Rng`/`RngCore` → `RngExt`)
- `ringmap` 0.1 → 0.2
**Skipped:**
- `hashbrown` 0.14 → 0.16: The `raw` module was removed in 0.15 and
replaced with `HashTable` API. The codebase uses `RawTable`, `Bucket`,
`InsertSlot` extensively, requiring a non-trivial migration.