Fix custom value with /

[labuladong]

Even #1228 fix the double escape error, there still some issue about custom dynamic config.

When the custom config value has /, the golang net/http package will unescape it by default. see golang/go#7356

For example, if the config value is a json like {"key": "https://example.com/"}, the expected request should be:

/admin/v2/brokers/configuration/someConfig/%7B%22key%22%3A%20%22https%3A%2F%2Fexample.com%2F%22%7D

But the actual request will be this:

/admin/v2/brokers/configuration/someConfig/{"key": "https://example.com/"}

And it will causes 404 not found because / in the URL.

If you escape the value twice, it will be:

/admin/v2/brokers/configuration/someConfig/%257B%2522key%2522%253A%2520%2522https%253A%252F%252Fexample.com%252F%2522%257D

The solution is url.RawPath field in this golang/go@874a605 , we need to modify this part to add the RawPath field:

pulsar-client-go/pulsaradmin/pkg/rest/client.go

Lines 47 to 68 in aa090be

	func (c *Client) newRequest(method, path string) (*request, error) {
	base, err := url.Parse(c.ServiceURL)
	if err != nil {
	return nil, err
	}
	u, err := url.Parse(path)
	if err != nil {
	return nil, err
	}
	req := &request{
	method: method,
	url: &url.URL{
	Scheme: base.Scheme,
	User: base.User,
	Host: base.Host,
	Path: endpoint(base.Path, u.Path),
	},
	params: make(url.Values),
	}
	return req, nil
	}

But the newRequest is used by many other methods, I don't want to touch it. So an easy solution is to provide a MakeRequestWithURL method, users can use it to customize.

[tuteng]

Sorry, I thought it was approved after the approve run test

[tuteng]

This pr LGTM