keys/ui: Add hotkey and command to generate new random footer hint.

Added tests.
Hotkeys document regenerated.

Author: Niloth-p

docs/hotkeys.md

@@ -13,6 +13,7 @@
 |Redraw screen|<kbd>Ctrl</kbd> + <kbd>l</kbd>|
 |Quit|<kbd>Ctrl</kbd> + <kbd>c</kbd>|
 |Show/hide user information (from users list)|<kbd>i</kbd>|
+|New footer hotkey hint|<kbd>Tab</kbd>|
 
 ## Navigation
 |Command|Key Combination|

tests/ui/test_ui.py

@@ -341,6 +341,23 @@ def test_keypress_STREAM_MESSAGE(
         assert returned_key == key
         assert view.body.focus_col == 1
 
+    @pytest.mark.parametrize("key", keys_for_command("NEW_HINT"))
+    def test_keypress_NEW_HINT(
+        self,
+        view: View,
+        mocker: MockerFixture,
+        key: str,
+        widget_size: Callable[[Widget], urwid_Box],
+    ) -> None:
+        size = widget_size(view)
+        set_footer_text = mocker.patch(VIEW + ".set_footer_text")
+        mocker.patch(CONTROLLER + ".is_in_editor_mode", return_value=False)
+
+        returned_key = view.keypress(size, key)
+
+        set_footer_text.assert_called_once_with()
+        assert returned_key == key
+
     @pytest.mark.parametrize("key", keys_for_command("SEARCH_PEOPLE"))
     @pytest.mark.parametrize("autohide", [True, False], ids=["autohide", "no_autohide"])
     def test_keypress_autohide_users(

zulipterminal/config/keys.py

@@ -438,6 +438,11 @@ class KeyBinding(TypedDict):
         'help_text': 'Show/hide full raw message (from message information)',
         'key_category': 'msg_actions',
     },
+    'NEW_HINT': {
+        'keys': ['tab'],
+        'help_text': 'New footer hotkey hint',
+        'key_category': 'general',
+    },
 }
 # fmt: on
 

zulipterminal/ui.py

@@ -328,6 +328,9 @@ def keypress(self, size: urwid_Box, key: str) -> Optional[str]:
         elif is_command_key("MARKDOWN_HELP", key):
             self.controller.show_markdown_help()
             return key
+        elif is_command_key("NEW_HINT", key):
+            self.set_footer_text()
+            return key
         return super().keypress(size, key)
 
     def mouse_event(