Fix: close the view if cmp.enabled = false and the user types some text (#781)

A scenario where this lead to unintended behaviour previously was the following:

If cmp.enabled was configured such that it disabled cmp when in a comment,
and the user typed '--' in a lua file (this starts a comment), the cmp window
would not close if further text is typed on that line (although cmp should be disabled).

lua/cmp/init.lua

@@ -309,12 +309,18 @@ end)
 autocmd.subscribe('TextChanged', function()
   if config.enabled() then
     cmp.core:on_change('TextChanged')
+  else
+    cmp.core:reset()
+    cmp.core.view:close()
   end
 end)
 
 autocmd.subscribe('CursorMoved', function()
   if config.enabled() then
     cmp.core:on_moved()
+  else
+    cmp.core:reset()
+    cmp.core.view:close()
   end
 end)