Short-circuit API rate limiter for unauthenticated users (#607)

### Major
- Short-circuit API rate limiter for unauthenticated user
  Calls by unauthenticated users were failing at API rate limiter as it
  failed to access user info object. This is a bug.
  
  API rate limiter should short-circuit for unauthenicated users so a
  proper Forbidden response can be returned by API
  
  Add regression test to verify that unauthenticated users get 403
  response when calling the /chat API endpoint
  
### Minor
- Remove trailing slash to normalize khoj url in obsidian plugin settings
- Move used /api/config API controllers into separate module
- Delete unused /api/beta API endpoint
- Fix error message rendering in khoj.el, khoj obsidian chat
- Handle deprecation warnings for subscribe renew date, langchain, pydantic & logger.warn

src/interface/obsidian/src/chat_modal.ts

@@ -245,7 +245,7 @@ export class KhojChatModal extends Modal {
             if (responseJson.detail) {
                 // If the server returns error details in response, render a setup hint.
                 let setupMsg = "Hi 👋🏾, to start chatting add available chat models options via [the Django Admin panel](/server/admin) on the Server";
-                this.renderMessage(chatBodyEl, setupMsg, "khoj", undefined, true);
+                this.renderMessage(chatBodyEl, setupMsg, "khoj", undefined);
 
                 return false;
             } else if (responseJson.response) {

src/interface/obsidian/src/settings.ts

@@ -42,7 +42,7 @@ export class KhojSettingTab extends PluginSettingTab {
             .addText(text => text
                 .setValue(`${this.plugin.settings.khojUrl}`)
                 .onChange(async (value) => {
-                    this.plugin.settings.khojUrl = value.trim();
+                    this.plugin.settings.khojUrl = value.trim().replace(/\/$/, '');
                     await this.plugin.saveSettings();
                     containerEl.firstElementChild?.setText(this.getBackendStatusMessage());
                 }));