Add option to disable ES transforms in `sucrase`

`tsup` uses `sucrase` to transpile ESM to CJS when code splitting is enabled:

https://github.com/egoist/tsup/blob/83c7c7f3131ca6d46aaad4de3111c2fd5e5b5c21/src/plugins/cjs-splitting.ts#L21-L31

Unfortunately there is no way right now to specify the settings for `sucrase`. In our case, we wanted to disable the optional chaining polyfill that `sucrase` adds, since it's problematic for static analysis. The only way to do so seems to be by setting `disableESTransforms: true` in the options. It would be great if `tsup` had an option to set this.

Start in src/plugins/cjs-splitting.ts at the linked Sucrase call, then trace how tsup exposes build options. Check how the disableESTransforms setting can reach Sucrase without changing existing code-splitting behavior. Done means users can configure that option and the generated CJS no longer applies the unwanted optional-chaining transform.

Written by the indexing model from the issue text.