Http2 Stream Reset Rate Limit Config

Added :ref:stream_reset_burst <envoy_v3_api_field_config.core.v3.Http2ProtocolOptions.stream_reset_burst> and :ref:stream_reset_rate <envoy_v3_api_field_config.core.v3.Http2ProtocolOptions.stream_reset_rate> fields to Http2ProtocolOptions. These configure the token-bucket RST_STREAM rate limiter built into nghttp2 (CVE-2023-44487 / HTTP/2 Rapid Reset protection) for server-side connections. The defaults (burst=1000, rate=33/sec) match the existing nghttp2 behavior; operators can raise these limits when legitimate workloads (e.g. gRPC streaming with many short-lived streams that receive RST_STREAM on RESOURCE_EXHAUSTED) exhaust the budget faster than it replenishes. These options only apply when using nghttp2 as a server.