Add initial support for code metadata (#1840)

See https://github.com/WebAssembly/tool-conventions/blob/main/CodeMetadata.md  for the specification.

In particular this pr implements the following:

- Parsing code metadata sections in BinaryReader, providing appropriate callbacks that a BinaryReaderDelegate can implement:
    - BinaryReaderObjdump: show the sections in a human-readable form
    - BinaryReaderIr: add code metadata in the IR as expressions
- Parsing code metadata annotations in text format, adding them in the IR like the BinaryReaderIR does
- Writing the code metadata present in the IR in the proper sections when converting IR to binary
- Support in wasm-decompiler for showing code metadata as comments in the pseudo-code

All the features have corresponding tests.

Support for code metadata is gated through the --enable-code-metadata feature. For reading/writing in the text format, --enable-annotations is also required.

Missing features:

    Support for function-level code metadata (offset 0)
    Extensive validation in validator.cc (like making sure that all metadata instances are at the same code offset of an instruction)

1 files changed, 15 insertions, 0 deletions

diff --git a/src/binary-reader-nop.h b/src/binary-reader-nop.h
index 4adde26a..ff78aa7f 100644
--- a/src/binary-reader-nop.h
+++ b/src/binary-reader-nop.h
@@ -462,6 +462,21 @@ class BinaryReaderNop : public BinaryReaderDelegate {
   Result OnTagType(Index index, Index sig_index) override { return Result::Ok; }
   Result EndTagSection() override { return Result::Ok; }
 
+  /* Code Metadata sections */
+  Result BeginCodeMetadataSection(std::string_view name, Offset size) override {
+    return Result::Ok;
+  }
+  Result OnCodeMetadataFuncCount(Index count) override { return Result::Ok; }
+  Result OnCodeMetadataCount(Index function_index, Index count) override {
+    return Result::Ok;
+  }
+  Result OnCodeMetadata(Offset offset,
+                        const void* data,
+                        Address size) override {
+    return Result::Ok;
+  }
+  Result EndCodeMetadataSection() override { return Result::Ok; }
+
   /* Dylink section */
   Result BeginDylinkSection(Offset size) override { return Result::Ok; }
   Result OnDylinkInfo(uint32_t mem_size,