resources: Add more details to .Err

This commit adds a .Data object (a map with `Body`, `StatusCode` etc.) to the .Err returned from `resources.GetRemote`, which means you can now do:

```
{{ with .Err }}
{{ range $k, $v := .Data }}
{{ end }}
{{ end }}
```

Fixes #9708

resources/page/page_nop.go

@@ -48,7 +48,7 @@ var (
 // PageNop implements Page, but does nothing.
 type nopPage int
 
-func (p *nopPage) Err() error {
+func (p *nopPage) Err() resource.ResourceError {
 	return nil
 }
 

resources/page/testhelpers_test.go

@@ -120,7 +120,7 @@ type testPage struct {
 	sectionEntries []string
 }
 
-func (p *testPage) Err() error {
+func (p *testPage) Err() resource.ResourceError {
 	return nil
 }