Pass multiple allowed Khoj domains via KHOJ_DOMAIN env var

To add multiple allowed Khoj domains pass them as a comma separated
list of domains via the KHOJ_DOMAIN environment variable

Resolve comment in issue #662

src/khoj/main.py

@@ -3,6 +3,7 @@
 """
 
 from contextlib import redirect_stdout
+import itertools
 import logging
 import io
 import os
@@ -66,19 +67,25 @@ else:
 django_app = get_asgi_application()
 
 # Add CORS middleware
-KHOJ_DOMAIN = os.getenv("KHOJ_DOMAIN", "app.khoj.dev")
+KHOJ_DOMAIN = os.getenv("KHOJ_DOMAIN", "app.khoj.dev").split(",")
+scheme = "https" if not is_env_var_true("KHOJ_NO_HTTPS") else "http"
+custom_origins = list(
+    itertools.chain.from_iterable(
+        [[f"{scheme}://{domain.strip()}", f"{scheme}://{domain.strip()}:*"] for domain in KHOJ_DOMAIN]
+    )
+)
+default_origins = [
+    "app://obsidian.md",  # To allow access from Obsidian desktop app
+    "capacitor://localhost",  # To allow access from Obsidian iOS app using Capacitor.JS
+    "http://localhost",  # To allow access from Obsidian Android app
+    "http://localhost:*",  # To allow access from localhost
+    "http://127.0.0.1:*",  # To allow access from localhost
+    "app://khoj.dev",  # To allow access from Khoj desktop app
+]
+
 app.add_middleware(
     CORSMiddleware,
-    allow_origins=[
+    allow_origins=default_origins + custom_origins,
-        "app://obsidian.md",
-        "capacitor://localhost",  # To allow access from Obsidian iOS app using Capacitor.JS
-        "http://localhost",  # To allow access from Obsidian Android app
-        "http://localhost:*",
-        "http://127.0.0.1:*",
-        f"https://{KHOJ_DOMAIN}" if not is_env_var_true("KHOJ_NO_HTTPS") else f"http://{KHOJ_DOMAIN}",
-        f"https://{KHOJ_DOMAIN}:*" if not is_env_var_true("KHOJ_NO_HTTPS") else f"http://{KHOJ_DOMAIN}:*",
-        "app://khoj.dev",
-    ],
     allow_credentials=True,
     allow_methods=["*"],
     allow_headers=["*"],