Add onRedirectNavigate callback to stop navigatation and get redirect url

[jasonnutter]

This adds a new callback for loginRedirect and acquireTokenRedirect to allow applications to get the URL that would be navigated to, and to stop navigation. This is to support scenarios where applications want to perform the redirect themselves, instead of relying on MSAL.

Usage:

msal.loginRedirect({
  onRedirectNavigate: url => {
    // url that would be navigated to
    console.log(url);
   
     // Applications must explicitly return false to stop navigation
     return false;
  }
})

[coveralls]

Coverage increased (+0.05%) to 78.414% when pulling 7b68ffc on onRedirectNavigate into c6e60bd on dev.

[tnorling]

LGTM

[Inframatic]

How could one transform that received redirect URL and pass that in as the new redirect url?

My purpose would be editing the redirect url to remove the login_hint