[build] Upgrade rules_rs to 0.0.109 and @llvm to 0.8.19

[AutomatedTester]

Summary

Upgrades the Rust build toolchain to current releases:

• rules_rs 0.0.96 → 0.0.109 (this also advances the vendored
  rules_rust fork it bundles, commit b03f1b0 → e9dd49f)
• @llvm (hermetic-llvm) 0.8.11 → 0.8.19 (LLVM 23.1.0)

Dropped local patch

rules_rs 0.0.109 carries the zlib snapshot-URL fix upstream (its
rustc_repository.bzl now points at snapshot.ubuntu.com), so the local
rules_rs_zlib_snapshot.patch and its single_version_override are removed —
matching the existing "remove when updating to rules_rs >= 0.0.108" note.

Required API change

The rules_rs toolchains module extension no longer publishes a top-level
:all target for the generated toolchains repo, so registration uses the
recursive pattern:

-register_toolchains("@default_rust_toolchains//:all")
+register_toolchains("@default_rust_toolchains//...")

Validation

bazel build //rust:selenium-manager -c opt builds cleanly on macOS (arm64);
the resulting binary runs (selenium-manager 0.4.49-nightly).
./scripts/format.sh --pre-push passes.

Notes

• Shipped selenium-manager binaries are Cargo-built in CI; this change
  affects the Bazel (local/dev) build path only.
• @llvm 0.8.18 already added Windows cc_common linking and authoritative
  Windows ABI handling, and rules_rs exposes a configurable
  declare_rustc_toolchains macro — relevant groundwork for the in-progress
  Windows-host build of selenium-manager ([rust] Allow cross-compilation of selenium-manager on all platforms #17586), but not exercised here.

[titusfortner]

Sorry, I jumped over you on this one with #17997 and didn't close this. It needed a patch, and I PR'd the fix upstream as well.

[titusfortner]

Oh, I missed that there's a 109. Good times. I'll look at what it adds.