Improve SAFE_HEAP information in errors

Right now when an error happens it just aborts. Instead, it could mention the address it errors on and the value if relevant. Context is a comment by @juj:

https://groups.google.com/g/emscripten-discuss/c/xvcjByZKxVA/m/nFkwP1PdAQAJ

After the initial port of Emscripten to the wasm backend we added basic SAFE_HEAP support. Later we had sanitizers working, so SAFE_HEAP seemed less urgent to improve. But there are still cases where it helps, so further improvements might be worthwhile. It should be straightforward to add them, first in the SafeHeap pass in Binaryen and then in the JS side here.