refactor: views: Declare some local variables as member variables.

This is done in MsgInfoView, as it is an aspect for future commit.

zulipterminal/ui_tools/views.py

@@ -1120,6 +1120,7 @@ def __init__(self, controller: Any, msg: Message, title: str,
                  time_mentions: List[Tuple[str, str]],
                  ) -> None:
         self.msg = msg
+        self.controller = controller
         self.topic_links = topic_links
         self.message_links = message_links
         self.time_mentions = time_mentions
@@ -1161,9 +1162,10 @@ def __init__(self, controller: Any, msg: Message, title: str,
                     grouped_reactions[reaction] = user
             msg_info.append(('Reactions', list(grouped_reactions.items())))
 
-        popup_width, column_widths = self.calculate_table_widths(msg_info,
-                                                                 len(title))
-        widgets = self.make_table_with_categories(msg_info, column_widths)
+        self.popup_width, column_widths = (self.calculate_table_widths(
+                                           msg_info, len(title)))
+        self.widgets = (self.make_table_with_categories(
+                        msg_info, column_widths))
 
         if message_links:
             message_link_widgets = []
@@ -1184,11 +1186,12 @@ def __init__(self, controller: Any, msg: Message, title: str,
             # slice_index = Number of labels before message links + 1 newline
             #               + 1 'Message Links' category label.
             slice_index = len(msg_info[0][1]) + 2
-            widgets = (widgets[:slice_index] + message_link_widgets
-                       + widgets[slice_index:])
-            popup_width = max(popup_width, message_link_width)
+            self.widgets = (self.widgets[:slice_index] + message_link_widgets
+                            + self.widgets[slice_index:])
+            self.popup_width = max(self.popup_width, message_link_width)
 
-        super().__init__(controller, widgets, 'MSG_INFO', popup_width, title)
+        super().__init__(self.controller, self.widgets, 'MSG_INFO',
+                         self.popup_width, title)
 
     def keypress(self, size: urwid_Size, key: str) -> str:
         if (is_command_key('EDIT_HISTORY', key)