Partial for #36421

`bento-*.js` files now use shared modules from a global `BENTO`. 

Shared modules are listed on `shared-bento-symbols.js`.

- We generate `bento.js` to import and provide the dependencies based on this list. We also generate `bento-shared.js` to use the dependencies from the global.

- `bento-*.js` binaries use `module-resolver` so that the listed imports are replaced with `bento-shared.js`.

Also adds the flag `--bento_runtime_only`.