[Object][Wasm] Generate symbol info from name section names (#81063)

Currently symbol info is generated from a linking section or from export
names. This PR generates symbols in a WasmObjectFile from the name
section as well, which allows tools like objdump and nm to show useful
information for more linked binaries. There are some limitations:
most notably that we don't assume any particular ABI, so we don't get
detailed information about data symbols if the segments are merged
(which is the default).

Covers most of the desired functionality from #76107