NbDummyAuthStrategy missing option to set redirect path

[giacomo]

Issue type

I'm submitting a ... (check one with "x")

• [ ] bug report
• [x] feature request

Issue description

Current behavior: NbDummyAuthStrategy has no option to set redirect path after "successful" login. Hardcoded value redirects to /.

https://github.com/akveo/nebular/blob/master/src/framework/auth/strategies/dummy/dummy-strategy.ts#L67

return new NbAuthResult(true, this.createSuccessResponse(data), '/', [], ['Successfully logged in.'], token);

Expected behavior:

redirect option could be set if needed, as example:

export class NbDummyAuthStrategyOptions extends NbAuthStrategyOptions {
  token?: NbStrategyToken = {
    class: NbAuthSimpleToken,
  };
  delay?: number = 1000;
  alwaysFail?: boolean = false;
  redirect?: string = '/';
}

Related code: https://github.com/akveo/nebular/blob/master/src/framework/auth/strategies/dummy/dummy-strategy-options.ts https://github.com/akveo/nebular/blob/master/src/framework/auth/strategies/dummy/dummy-strategy.ts