Allow specifying redirect url

[vanatteveldt]

Currently middlecat always sends the user back to the page it came from. It would be nice to allow an application to specify a path to redirect to on successful login. Concrete use-case: we have an amcat server landing page with a login button. After login, it should redirect to the index list rather than back to the landing page.

This would probably involve adding an argument to https://github.com/ccs-amsterdam/middlecat-react/blob/main/src/lib/middlecatOauth.ts#L8 so it can be added to the useMiddlecat hook signIn function [https://github.com/ccs-amsterdam/middlecat-react/blob/main/src/lib/middlecatOauth.ts#L8]