run: Add -n argument to login to a realm, and create config.

If the realm already exists, will exit with an error saying so.

Tests updated.

tests/cli/test_run.py

@@ -134,6 +134,7 @@ def test_main_help(capsys: CaptureFixture[str], options: str) -> None:
         "-h, --help",
         "-d, --debug",
         "-o, --list-organizations",
+        "-n, --new-organization",
         "--list-themes",
         "--profile",
         "--config-file CONFIG_FILE, -c CONFIG_FILE",

zulipterminal/cli/run.py

@@ -156,6 +156,12 @@ def parse_args(argv: List[str]) -> argparse.Namespace:
         action="store_true",
         help="list all the organizations that you have configurations for, and exit",
     )
+    parser.add_argument(
+        "-n",
+        "--new-organization",
+        action="store_true",
+        help="login to a new organization",
+    )
     parser.add_argument(
         "--theme",
         "-t",
@@ -293,15 +299,20 @@ def get_api_key(realm_url: str) -> Optional[Tuple[str, str, str, str]]:
     return None
 
 
-def fetch_zuliprc(zuliprc_path: str) -> str:
+def fetch_zuliprc(zuliprc_path: str, new_realm: bool) -> str:
     locations_checked = (
         zuliprc_path
         if zuliprc_path != ""
         else f"any of the following locations: "
         f"{DOWNLOADED_PATH_ZULIPRC} or {ZULIP_CONFIG_PATH} or {HOME_PATH_ZULIPRC}"
     )
+    missing_zuliprc_text = (
+        ""
+        if new_realm
+        else f"{in_color('red', f'zuliprc file was not found at {locations_checked}')}"
+    )
     print(
-        f"{in_color('red', f'zuliprc file was not found at {locations_checked}')}"
+        f"{missing_zuliprc_text}"
         f"\nPlease enter your credentials to login into your Zulip organization."
         f"\n"
         f"\nNOTE: The {in_color('blue', 'Zulip server URL')}"
@@ -387,15 +398,21 @@ def check_for_default_zuliprc() -> str:
     return ""
 
 
-def parse_zuliprc(zuliprc_str: str) -> Tuple[Dict[str, SettingData], str]:
+def parse_zuliprc(
+    zuliprc_str: str, new_realm: bool
+) -> Tuple[Dict[str, SettingData], str]:
     zuliprc_path = (
-        check_for_default_zuliprc()
-        if zuliprc_str == ""
-        else path.expanduser(zuliprc_str)
+        (
+            check_for_default_zuliprc()
+            if zuliprc_str == ""
+            else path.expanduser(zuliprc_str)
+        )
+        if not new_realm
+        else ""
     )
     while zuliprc_path == "" or not path.exists(zuliprc_path):
         try:
-            zuliprc_path = fetch_zuliprc(zuliprc_path)
+            zuliprc_path = fetch_zuliprc(zuliprc_path, new_realm)
         # Invalid user inputs (e.g. pressing arrow keys) may cause ValueError
         except (OSError, ValueError):
             # Remove zuliprc file if created.
@@ -552,7 +569,7 @@ def main(options: Optional[List[str]] = None) -> None:
     )
 
     try:
-        zterm, zuliprc_path = parse_zuliprc(zuliprc_path)
+        zterm, zuliprc_path = parse_zuliprc(zuliprc_path, args.new_organization)
 
         ### Validate footlinks settings (not from command line)
         if (