feat!: decouple wasmer from Marine, replace it with generic backend interface (#219)

crates/wasm-backend-traits/src/impl_utils.rs

@@ -0,0 +1,24 @@
+pub use multimap::MultiMap;
+
+pub fn custom_sections(bytes: &[u8]) -> Result<MultiMap<String, Vec<u8>>, String> {
+    use wasmparser::Parser;
+    use wasmparser::Payload;
+
+    Parser::new(0)
+        .parse_all(bytes)
+        .filter_map(|payload| {
+            let payload = match payload {
+                Ok(payload) => payload,
+                Err(e) => return Some(Err(e.to_string())),
+            };
+            match payload {
+                Payload::CustomSection(reader) => {
+                    let name = reader.name().to_string();
+                    let data = reader.data().to_vec();
+                    Some(Ok((name, data)))
+                }
+                _ => None,
+            }
+        })
+        .collect()
+}