fix: if pages and resources view is disabled, show all pages in studio (#30550)

In a previous PR #28686, the ability to see and enable/disable wiki and progress tabs was removed from studio along with the ability to re-order non-static tabs. The ability to toggle the Wiki tab was moved to the pages and resources section of the course authoring MFE. If that MFE is unavailable this means there is no way to show/hide the Wiki. This reverts some of the old changes if the pages and resources view is disabled.

xmodule/tabs.py

@@ -53,7 +53,7 @@ class CourseTab(metaclass=ABCMeta):
     priority = None
 
     # Class property that specifies whether the tab can be moved within a course's list of tabs
-    is_movable = True
+    is_movable = False
 
     # Class property that specifies whether the tab is a collection of other tabs
     is_collection = False
@@ -301,6 +301,7 @@ class StaticTab(CourseTab):
     """
     type = 'static_tab'
     is_default = False  # A static tab is never added to a course by default
+    is_movable = True
     allow_multiple = True
     priority = 100