feat(net): Update Fork Filter At Runtime

[refcell]

Summary

Adds a set_fork_filter method to the NetworkSyncUpdater trait and NetworkHandle, letting a running node replace its active ForkFilter without a restart. The network manager routes the new SetForkFilter handle message through the session manager, which swaps in the new filter and re-derives the advertised ForkId so future handshakes announce the updated fork identity. This lets a node adopt a fork schedule that changes at runtime (e.g. an L1-signalled upgrade) and stay aligned with the rules it now enforces instead of advertising a stale fork id and getting partitioned. The trait method defaults to a no-op so updaters that do not track a fork filter are unaffected.

CI note

The failing clippy, docs, and deny checks are pre-existing on the base branch and unrelated to this change. This PR modifies only 4 source files and adds no dependencies; those files are clippy- and docs-clean. The clippy failures are nightly-toolchain churn in untouched files (needless_range_loop in test_utils/testnet.rs, needless_bool in transactions/fetcher.rs), and deny reports pre-existing dependency advisories.

[refcell]

Superseded by the automated reth-prepare-release flow. paradigmxyz#26794 is now squashed into the base-v2.5.1.2 fork tag on backport/v2.5.1/main, and base/base is pinned to it in base/base#4740. Closing this manual backport as redundant.