Invalid sourcemap due to missing TS output files in package

While diagnosing and fixing https://github.com/js-temporal/temporal-polyfill/issues/192, I found that JSBI has the same bug: the package's sourcemap points to files that don't exist in the package. This causes debug console errors in some environments like the VSCode debugger.

For example, here's what I see in the debug console when I run my JSBI-using app in the VSCode debugger:

```
Could not read source map for file:///Users/[redacted for privacy]/node_modules/jsbi/tsc-out/jsbi.mjs: ENOENT: no such file or directory, open '/Users/[redacted for privacy]/node_modules/jsbi/tsc-out/jsbi.js.map'
```

The fix that I proposed in https://github.com/js-temporal/temporal-polyfill/pull/193 is to add the `tsc-out` folder to the package. The `lib` folder should also be added. I suspect that the same fix may work here too. There may be other fixes possible too.