Align TS replace() signuatrue return with implementaiton

[danielmoore]

This PR changes the TypeScript type definition for td.replace() to return any instead of void.

Per the documentation:

td.replace(object, propertyName, [manualReplacement])

[...]
td.replace typically returns the fake thing it sets on object, with the
exception of constructor function properties. In that case, it will return a
plain object of test double functions to the test, but set object[propertyName]
to a constructor function that delegates to those test double functions only
after it's been instantiated with new.

and

td.replace(relativePathToModule, [manualReplacement])

[...]
Once defined, it will return a fake thing based on the same
inferences discussed above and replace subsequent calls to require for that
module until the next call to td.reset()

---

For any downstream users who need these changes sooner, you can add a file to your code named something like testdouble-overrides.d.ts with the following content:

import 'testdouble';

declare module 'testdouble' {
  export function replace(path: string, f?: any): any;
  export function replace(path: {}, property: string, f?: any): any;
}

[searls]

I'll have to take your word for it but it seems legit