Volunteer can toggle to volunteer login

[maggie-larkin]

Notes

• See here for design, no need to worry about the cute graphics at the moment
• Some of this functionality exists here but this would allow the toggle between foster and volunteer

User Story

As a volunteer for The Little Black Dog
I want to log into the system
So that I can see the list of fosters

Acceptance Criteria

GIVEN I am on the login page

WHEN I toggle to "Volunteer"

THEN I see a field labeled "Email"
AND I see a field labeled "Password"
AND I see a button that says "Login"