[Minor] Add convenience method to set plugin state

lualib/lua_util.lua

@@ -199,4 +199,23 @@ end
 
 exports.spairs = spairs
 
+local function disable_module(modname, how)
+  for i,mn in ipairs(rspamd_plugins_state.enabled) do
+    if modname == mn then
+      table.remove(rspamd_plugins_state.enabled, i)
+      break
+    end
+  end
+
+  if how == 'redis' then
+    table.insert(rspamd_plugins_state.disabled_redis, modname)
+  elseif how == 'config' then
+    table.insert(rspamd_plugins_state.disabled_unconfigured, modname)
+  else
+    table.insert(rspamd_plugins_state.disabled_failed, modname)
+  end
+end
+
+exports.disable_module = disable_module
+
 return exports