Add object Collaborator and mutation unitTypeCreate

[Lopidurs]

gql schema corresponding to those changes:

type Collaborator {
   id: ID!
   name: String!
   firstName: String!
}

type query {
   collaborators: [Collaborator!]!
   collaboratorById(id: ID!): Collaborator!
}

input UnitTypeCreateInput {
   name: String!
}

type mutation {
   unitTypeCreate(input: UnitTypeCreateInput!): UnitType
}