This is preliminary work for string interning in the wasm linker.
Using an arena would defeat the purpose of de-duplicating strings as we wouldn't be able to free memory
of duplicated strings.
This change also means we can simplify wasm binary parsing, by creating a general purpose parser that
parses the binary into its sections, but untyped. Doing this, allows us to re-use the base of that, for
object file, but also debug info parsing.