Move public ZSTD_copyCCtx pledge normalization and frame-parameter policy into
Rust while retaining the private workspace and match-table copy implementation
behind a C callback.
Test Plan:
- cargo test --manifest-path rust/Cargo.toml --lib
- cargo clippy --manifest-path rust/Cargo.toml --all-targets -- -D warnings
- make -B -C programs -j1 zstd
- make -C tests -j1 test-zstream ZSTREAM_TESTTIME=-T1s
- focused copy_cctx unit tests