Hstaykov/provider support for ws

[HristoStaykov]

Summary

• Websocket providers are promoted to first-class components by updating ProviderBuilder to use a resilient WS connector with configurable exponential backoff and reconnect metrics.
• Reorg tracking is updated to use the same reconnection policy, removing one-off retry logic and ensuring polling continues while the next WS retry is scheduled.
• New websocket_reconnect configuration options are added (with defaults and validation), provider tests are updated, new Prometheus counters are exposed, and the behavior is documented in README / Reorg.md.

Details

• Introduces apps/sequencer/src/providers/ws.rs containing ResilientWsConnect, a shared WsReconnectPolicy, a metrics-hook trait, and unit tests that exercise the retry loop and backoff behavior.
• The new connector is integrated into both the primary RpcProvider (including async-trait metrics recording) and the ReorgTracker, replacing custom backoff logic with the shared policy and state.
• Adds WebsocketReconnectConfig in libs/config, threads it through the sequencer setup, and registers six new websocket reconnect/disconnect counters in ProviderMetrics.
• Updates documentation (README, new Reorg.md) and configuration/test fixtures to describe the optional reconnect policy alongside the existing websocket URL.