feat(compress): move deprecated block-size formula to Rust

Keep validation of the applied compression parameters in C and delegate the context-free minimum calculation through a narrow ABI leaf. Preserve the public getter and deprecated block-compression paths.

Test Plan:

- cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression

- cargo clippy --manifest-path rust/Cargo.toml --no-default-features --features compression --all-targets

- cargo +nightly fmt --manifest-path rust/Cargo.toml

- make -B -C lib -j2 lib

- make -C tests -j2 fuzzer

- tests/fuzzer -s4560 -t47 -i48 -v

lib/compress/zstd_compress.c

@@ -103,6 +103,7 @@ ZSTD_parameters ZSTD_rust_params_makeParams(ZSTD_compressionParameters cParams);
 size_t ZSTD_rust_params_maxNbSeq(size_t blockSize, U32 minMatch,
                                  int useSequenceProducer);
 size_t ZSTD_rust_params_resolveMaxBlockSize(size_t maxBlockSize);
+size_t ZSTD_rust_params_getBlockSize(size_t maxBlockSize, U32 windowLog);
 int ZSTD_rust_params_rowMatchFinderSupported(int strategy);
 int ZSTD_rust_params_rowMatchFinderUsed(int strategy, int mode);
 int ZSTD_rust_params_resolveRowMatchFinderMode(
@@ -3350,7 +3351,7 @@ static size_t ZSTD_getBlockSize_deprecated(const ZSTD_CCtx* cctx)
 {
     ZSTD_compressionParameters const cParams = cctx->appliedParams.cParams;
     assert(!ZSTD_checkCParams(cParams));
-    return MIN(cctx->appliedParams.maxBlockSize, (size_t)1 << cParams.windowLog);
+    return ZSTD_rust_params_getBlockSize(cctx->appliedParams.maxBlockSize, cParams.windowLog);
 }
 
 /* NOTE: Must just wrap ZSTD_getBlockSize_deprecated() */