Replace all "Filter" field with "Filters" for consistency

In file `api/types/client.go`, some of the "*Options{}" structs own a
`Filters` field while some else have the name of `Filter`, this commit
will rename all `Filter` to `Filters` for consistency. Also `Filters`
is consistent with API with format `/xxx?filters=xxx`, that's why
`Filters` is the right name.

Signed-off-by: Zhang Wei <zhangwei555@huawei.com>

node_list.go

@@ -14,8 +14,8 @@ import (
 func (cli *Client) NodeList(ctx context.Context, options types.NodeListOptions) ([]swarm.Node, error) {
 	query := url.Values{}
 
-	if options.Filter.Len() > 0 {
-		filterJSON, err := filters.ToParam(options.Filter)
+	if options.Filters.Len() > 0 {
+		filterJSON, err := filters.ToParam(options.Filters)
 
 		if err != nil {
 			return nil, err