add candidate form

[meganrm]

[WIP] - https://github.com/townhallproject/admin/compare/feature/candidates?expand=1

• The user has to select either 'campaign' or 'current office' (can also select both) before being allowed to "add to the database"
• Once they submit the person information, that should be displayed as a card instead of the form and the form should be hidden.
• Once the user has filled out the campaign and/or current office info, the whole system should reset to a new blank person form and give a success message