feat(volo-grpc): expose http2_max_pending_accept_reset_streams on Server

[icn5381]

References

Closes #657

Why

The underlying hyper/h2 server already supports capping the number of remotely-reset streams pending acceptance before the connection is closed (max_pending_accept_reset_streams, defaulting to 20 in h2), but volo-grpc's Server didn't expose this knob. Under load with frequent stream resets, this surfaces as repeated warnings:

recv_reset; remotely-reset pending-accept streams reached limit (20)

with no way for the application to raise the limit.

What changed

Added Server::http2_max_pending_accept_reset_streams, following the exact same Http2Config passthrough pattern already used by the sibling setters (http2_max_concurrent_streams, http2_max_header_list_size, http2_max_frame_size, etc.):

• New Http2Config::max_pending_accept_reset_streams: Option<usize> field, defaulting to None (unchanged behavior — hyper's own default of 20 still applies).
• New builder method Server::http2_max_pending_accept_reset_streams(max: impl Into<Option<usize>>).
• Wired into the hyper_util HTTP/2 builder alongside the other http2_* config calls.

This is purely additive — no existing behavior changes, no new dependencies (the method already exists on hyper_util::server::conn::auto::Http2Builder).

Surface area

• New feature (non-breaking change which adds functionality)

Validation

cargo build -p volo-grpc --all-features
cargo clippy -p volo-grpc --all-features
cargo fmt -p volo-grpc -- --check
cargo test -p volo-grpc http2_max_pending_accept_reset_streams

All pass. Added two unit tests (http2_max_pending_accept_reset_streams_defaults_to_none, http2_max_pending_accept_reset_streams_sets_value) covering the default and the builder wiring — the crate had no prior unit tests for the sibling http2_* config setters to follow, so this establishes the pattern for this one field.

AI assistance

• Tool(s) used: Claude Code
• How you used it: AI verified the exact hyper/h2 API surface (hyper_util::server::conn::auto::Http2Builder::max_pending_accept_reset_streams) matches the reporter's proposed API, implemented the field/builder/wiring following the existing Http2Config pattern, and wrote the two unit tests.
• Human verification: Read and understood every line of this change; confirmed via the vendored hyper/hyper-util source that the method exists with the expected signature before writing any code; ran cargo build/clippy/fmt --check/test myself and confirmed all pass; confirmed the change only touches volo-grpc/src/server/mod.rs with no unrelated edits; take responsibility for this change.
• I've read and understand every line of this change and take responsibility for it.

[CLAassistant]

All committers have signed the CLA.

[icn5381]

I have read the CLA Document and I hereby sign the CLA behalf on myself, e-mail: 255778606+icn5381@users.noreply.github.com