Add email password example

[lyqht]

Right now in the supertokens-react-native library, we only have an example for the thirdpartyemailpassword, I would like to add an example for emailpassword (like the with-emailpassword example in supertokens-auth-react)

[rishabhpoddar]

@lyqht this is a great idea. If you need assistance with the example, please let us know.

[rishabhpoddar]

The example that exists right now uses thirdpartyemailpassword on the backend, but the frontend doesn't have an email / password input. Maybe you can change the current example to have that?