Fix missing signature key error when pulling Docker images with SERVE_DIRECT enabled (#32365)

Fix #28121

I did some tests and found that the `missing signature key` error is
caused by an incorrect `Content-Type` header. Gitea correctly sets the
`Content-Type` header when serving files.

348d1d0f32/routers/api/packages/container/container.go (L712-L717)
However, when `SERVE_DIRECT` is enabled, the `Content-Type` header may
be set to an incorrect value by the storage service. To fix this issue,
we can use query parameters to override response header values.

https://docs.aws.amazon.com/AmazonS3/latest/API/API_GetObject.html
<img width="600px"
src="https://github.com/user-attachments/assets/f2ff90f0-f1df-46f9-9680-b8120222c555"
/>

In this PR, I introduced a new parameter to the `URL` method to support
additional parameters.

```
URL(path, name string, reqParams url.Values) (*url.URL, error)
```

---

Most S3-like services support specifying the content type when storing
objects. However, Gitea always use `application/octet-stream`.
Therefore, I believe we also need to improve the `Save` method to
support storing objects with the correct content type.

b7fb20e73e/modules/storage/minio.go (L214-L221)

modules/storage/helper_test.go

@@ -37,7 +37,7 @@ func Test_discardStorage(t *testing.T) {
 				assert.Error(t, err, string(tt))
 			}
 			{
-				got, err := tt.URL("path", "name")
+				got, err := tt.URL("path", "name", nil)
 				assert.Nil(t, got)
 				assert.Errorf(t, err, string(tt))
 			}