feat(progress): disable cmdline progress msg via messagesopt' #36730

Problem:
No way to disable progress messages in cmdline message area. If
a third-party plugin handles Progress events + messages, the user may
not want the "redundant" progress displayed in the cmdline message area.

Solution:
Support "progress:c" entry in 'messageopts' option.

test/old/testdir/setup.vim

@@ -18,6 +18,7 @@ if exists('s:did_load')
   set laststatus=1
   set listchars=eol:$
   set maxsearchcount=99
+  set messagesopt=hit-enter,history:500
   set mousemodel=extend
   set nohidden nosmarttab noautoindent noautoread
   set nohlsearch noincsearch