Adding Chat apis

[Sma1lboy]

type Query {
getChatHistory(chatId: ID!): [Message!]!
modelTags: ModelTags!
getChatDetails(chatId: ID!): Chat
}

type Mutation {
createChat: Chat!
deleteChat(chatId: ID!): Boolean!
clearChatHistory(chatId: ID!): Boolean!
updateChatTitle(chatId: ID!, title: String!): Chat!
}

type Subscription {
chatStream(input: ChatInput!): ChatCompletionChunk //Already done
}

type Chat {
id: ID!
title: String
messages: [Message!]!
createdAt: String!
updatedAt: String!
}

type User {
chats: [Chat!]
}