core/messages: Display message sender information on hotkey 'u'.

Defines method show_msg_sender_info which renders a popup that shows
user information for a message sender, and is triggered when key 'u' is
pressed on an active MessageBox.

Fixes #1397.

Author: israelsgalaxy

zulipterminal/core.py

@@ -320,6 +320,17 @@ def show_user_info(self, user_id: int) -> None:
             "area:user",
         )
 
+    def show_msg_sender_info(self, user_id: int) -> None:
+        self.show_pop_up(
+            UserInfoView(
+                self,
+                user_id,
+                "Message Sender Information (up/down scrolls)",
+                "MSG_SENDER_INFO",
+            ),
+            "area:user",
+        )
+
     def show_full_rendered_message(
         self,
         message: Message,

zulipterminal/ui_tools/messages.py

@@ -1110,4 +1110,6 @@ def keypress(self, size: urwid_Size, key: str) -> Optional[str]:
             )
         elif is_command_key("ADD_REACTION", key):
             self.model.controller.show_emoji_picker(self.message)
+        elif is_command_key("MSG_SENDER_INFO", key):
+            self.model.controller.show_msg_sender_info(self.message["sender_id"])
         return key