feat: add preset and edit preset.

client/src/store/preset.js

@@ -0,0 +1,40 @@
+import endpoints from './endpoints';
+import { atom, selector, useSetRecoilState, useResetRecoilState, useRecoilCallback } from 'recoil';
+
+// preset structure is as same defination as conversation
+// sample structure
+// {
+//   presetId: 'new',
+//   title: 'New Chat',
+//   user: null,
+//   // endpoint: [azureOpenAI, openAI, bingAI, chatGPTBrowser]
+//   endpoint: 'azureOpenAI',
+//   // for azureOpenAI, openAI, chatGPTBrowser only
+//   model: 'gpt-3.5-turbo',
+//   // for azureOpenAI, openAI only
+//   chatGptLabel: null,
+//   promptPrefix: null,
+//   temperature: 1,
+//   top_p: 1,
+//   presence_penalty: 0,
+//   frequency_penalty: 0,
+//   // for bingAI only
+//   jailbreak: false,
+//   jailbreakConversationId: null,
+//   conversationSignature: null,
+//   clientId: null,
+//   invocationId: 1,
+//   toneStyle: null,
+// };
+
+// an array of saved presets.
+// sample structure
+// [preset1, preset2, preset3]
+const presets = atom({
+  key: 'presets',
+  default: []
+});
+
+export default {
+  presets
+};