Expose setCurrentInvoke in typings

Could you please add a TypeScript export for the `setCurrentInvoke` function?
[current-invoke.d.ts](https://github.com/vendia/serverless-express/blob/mainline/src/current-invoke.d.ts) only exposes `getCurrentInvoke`.
This is needed to set event and context when debugging locally using `app.local.ts`

Start with src/current-invoke.d.ts, which currently exposes getCurrentInvoke. Add the TypeScript export for setCurrentInvoke so app.local.ts can set the event and context while debugging locally; done means the function is available to typings users alongside getCurrentInvoke.

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