wit-bindgen 0.41

[rvolosatovs]

Merge upstream wit-bindgen 0.41.0 into the vendored bindgen subtree.

• Bump wit-bindgen-core 0.40 -> 0.41 (wit-parser stays 0.227).
• Carry upstream's gen -> r#gen rename of the InterfaceGenerator field (and
  the gen locals in lib.rs) so interface.rs/lib.rs match upstream
  verbatim, including at the three additional_derive_ignore sites.
• Port upstream feature feat: Allow variants and records to be ignored by additional_derives wit-bindgen#1199 (additional_derives_ignore): variants and records
  named in this kebab-case list are excluded when applying additional_derives,
  so a type whose payload doesn't implement an added trait (e.g. a resource
  handle vs serde::Deserialize) keeps the bindings compiling. The macro half
  (crates/wit-bindgen-rust-macro) merged cleanly; reimplemented the generator
  half against wRPC's Opts (new additional_derive_ignore field + preamble
  log) and the three derive sites in interface.rs (record/variant/enum), each
  gated by !additional_derive_ignore.contains(&name.to_kebab_case()).
• Make wRPC's value-codec decoder generation edition-2024-clean: drop the
  explicit ref mut bindings in the three generated decoder match patterns in
  interface.rs (the default binding mode yields &mut under both editions),
  so generated bindings compile under edition 2024 as well as 2021. This is
  validated by the dual-edition verify carried with the test subcommand below.
• Carry upstream feature Add a wit-bindgen test subcommand wit-bindgen#1192 (wit-bindgen test subcommand), vendored from
  upstream's crates/test into a new wit-bindgen-wrpc-test crate
  (crates/wit-bindgen-test) with the guest-Wasm-specific pieces removed. The
  CLI gains a wit-bindgen-wrpc test subcommand. lib.rs/config.rs track
  upstream verbatim (kept deny_unknown_fields); rust.rs keeps upstream's
  Edition enum and dual-edition verify (compiling generated bindings under
  both 2021 and 2024) but is host-adapted. Dropped as guest-Wasm: the C/WAT
  language backends and the custom external-runner (crates/test/src/{c,wat, custom}.rs), the wasmtime runner (runner.rs), and in lib.rs the wasm32
  component compilation/convert_p1_to_component, wasm-compose composition and
  wasmparser validation. Codegen tests run the generic tests/codegen/*.wit
  inputs (replacing the codegen_tests! macro harness, so
  crates/wit-bindgen-{rust,go}/tests/codegen.rs are deleted). Runtime tests
  live under tests/runtime/rust/<name>/ with runner+test worlds; since wRPC
  bindings are Invoke/Serve RPC stubs rather than guest components, the
  runner (client) and test (server) are linked into one host binary connected
  over an in-process TCP transport and run to completion, instead of being
  composed in a component runtime. go.rs is wRPC-specific (upstream has no Go
  backend at this version). feat: Allow variants and records to be ignored by additional_derives wit-bindgen#1199's custom-derives test is ported here as a
  runtime test, behaviorally proving the derives apply (and that ignoreme is
  excluded), alongside ports of upstream's option tests (skip, with, with-types,
  with-option-generate, alternative-bitflags, gated-features, unused-types). The
  suite is driven under cargo test via tests/bindgen.rs, which invokes the
  subcommand through CARGO_BIN_EXE_wit-bindgen-wrpc.

Non-carries (not applicable to wRPC, dropped from the merge):

• upstream removed Go from its own tree (Go: Remove Go from wit-bindgen wit-bindgen#1195); wRPC keeps its own
  wit-bindgen-go generator.
• canonical-ABI / component-async / wasm-export-attribute changes (Complete support for rust 2024 edition wit-bindgen#1206/[wit-bindgen-rust] Fix 2024 edition compat wit-bindgen#1205
  rust 2024 edition export attrs, Automatic adaption to 64bit architectures in guest code wit-bindgen#1163 64-bit guest adaption, Store arguments for async params/results on the stack wit-bindgen#1185 async stack
  args, Update support for p3 to match the latest wasm-tools wit-bindgen#1198 p3) do not apply to wRPC's transport-stub generator.

wit-bindgen-wrpc test runs 172 codegen tests (86 WITs x rust/go, each rust case
verified under editions 2021 and 2024) and the runtime tests green; the whole
workspace builds; cargo clippy --workspace and cargo doc --workspace are
clean.

Assisted-by: claude:claude-opus-4-8
Upstream diff: bytecodealliance/wit-bindgen@v0.40.0...v0.41.0

[rvolosatovs]

I would have expected this PR to match upstream testing strategy (using wit-bindgen test)