fix: Make facility email field nullable

[evan-desu]

Previously we had placeholder email addresses in our database that we did not want to display in our SearchResultDetails component. This PR updates the GraphQL schema to to make facility email addresses nullable.

Part of #436

What changed

Remove non-nullable operator ! from GraphQL Contact type and ContactInput.

Testing instructions

Run npm run dev, navigate to http://127.0.0.1:4000/, and run the following mutation: Operation

mutation Mutation($input: CreateFacilityInput!) {
  createFacility(input: $input) {
    id
    nameEn
    contact {
      email
    }
    createdDate
    updatedDate
  }
}

Variables

{
  "input": {
    "contact": {
      "address": {
        "addressLine1En": "test",
        "addressLine1Ja": "テスト",
        "addressLine2En": "5555-55 test",
        "addressLine2Ja": "テスト5555-55",
        "cityEn": "test",
        "cityJa": "テスト",
        "postalCode": "123-0000",
        "prefectureEn": "test",
        "prefectureJa": "テスト"
      },
      //"email": null,
      "googleMapsUrl": "www.test.com",
      "phone": "080-1234-5678",
    },
    "healthcareProfessionalIds": "12345678",
    "mapLatitude": 1234,
    "mapLongitude": 5678,
    "nameEn": "Dr. test",
    "nameJa": "テスト先生"
  }
}

The response should include the field "email": null.

[ermish]

^ go ahead and merge when you're ready to verify it in prod @evan-desu