largefiles: use "ui.configlist()" to get largefiles.patterns configuration

current lfconvert implementation uses combination of "ui.config()" and
"str.split(' ')" to get largefiles.patterns configuration.

but it can not handle multiline configuration in hgrc files correctly.

lfconvert should use "ui.configlist()" instead of it, as same as
override_add does.

hgext/largefiles/lfcommands.py

@@ -71,9 +71,7 b' def lfconvert(ui, src, dest, *pats, **op'
             lfiles = set()
             normalfiles = set()
             if not pats:
-                pats = ui.config(lfutil.longname, 'patterns', default=())
-                if pats:
-                    pats = pats.split(' ')
+                pats = ui.configlist(lfutil.longname, 'patterns', default=[])
             if pats:
                 matcher = match_.match(rsrc.root, '', list(pats))
             else:

tests/test-lfconvert.t

@@ -5,7 +5,8 b''
   > graphlog =
   > [largefiles]
   > minsize = 0.5
-  > patterns = **.dat
+  > patterns = **.other
+  >     **.dat
   > EOF
 
 "lfconvert" works