Feat: add screen_hint param in /authorize api for explicit signup redirection (#420)

* Feat:
- Introduce screen_hint param in /authorize for explicit signup redirection

* Feat:
- Declare variable for base path and signup path
- Add social login on signup page

* Refactor:
- Update variable name for screen hint param

app/src/pages/signup.tsx

@@ -1,5 +1,5 @@
 import React, { Fragment } from 'react';
-import { AuthorizerSignup } from '@authorizerdev/authorizer-react';
+import { AuthorizerSignup, AuthorizerSocialLogin } from '@authorizerdev/authorizer-react';
 import styled from 'styled-components';
 import { Link } from 'react-router-dom';
 
@@ -19,6 +19,7 @@ export default function SignUp({
 		<Fragment>
 			<h1 style={{ textAlign: 'center' }}>Sign Up</h1>
 			<br />
+            <AuthorizerSocialLogin urlProps={urlProps} />
 			<AuthorizerSignup urlProps={urlProps} />
 			<FooterContent>
 				Already have an account? <Link to="/app"> Login</Link>