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, 1 insertions, 0 deletions

diff --git a/test/help/wast2json.txt b/test/help/wast2json.txt
index 90278883..95fa3a3e 100644
--- a/test/help/wast2json.txt
+++ b/test/help/wast2json.txt
@@ -28,6 +28,7 @@ options:
       --disable-bulk-memory                    Disable Bulk-memory operations
       --disable-reference-types                Disable Reference types (externref)
       --enable-annotations                     Enable Custom annotation syntax
+      --enable-code-metadata                   Enable Code metadata
       --enable-gc                              Enable Garbage collection
       --enable-memory64                        Enable 64-bit memory
       --enable-multi-memory                    Enable Multi-memory