progress: deprecate the progress extension

Activating it is a absolute no-op now.

hgext/progress.py

@@ -5,10 +5,8 b''
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
-"""show progress bars for some actions
+"""show progress bars for some actions (DEPRECATED)
 
-This extension uses the progress information logged by hg commands
-to draw progress bars that are as informative as possible. Some progress
-bars only offer indeterminate information, while others have a definite
-end point.
+This extension has been merged into core, you can remove it from your config.
+See hg help config.progress for configuration options.
 """

tests/test-help.t

@@ -264,7 +264,6 b' Test extension help:'
        notify        hooks for sending email push notifications
        pager         browse command output with an external pager
        patchbomb     command to send changesets as (a series of) patch emails
-       progress      show progress bars for some actions
        purge         command to delete untracked files from the working
                      directory
        record        commands to interactively select changes for