ExtraResources namespace is ignored when using matchLabels

### What happened?

`ExtraResources` with `matchLabels` and `namespace` appears to ignore `namespace`.

```yaml
apiVersion: meta.gotemplating.fn.crossplane.io/v1alpha1
kind: ExtraResources
requirements:
databaseResource:
apiVersion: mssql.sql.m.crossplane.io/v1alpha1
kind: Database
matchLabels:
app.kubernetes.io/managed-by: crossplane
app.kubernetes.io/component: database
namespace: test
```
ToResourceSelector() returns before setting Namespace when matchLabels is used:
https://github.com/crossplane-contrib/function-go-templating/blob/v0.12.2/extraresources.go#L39-L56
Possible fix:
```
func (e *ExtraResourcesRequirement) ToResourceSelector() *fnv1.ResourceSelector {
out := &fnv1.ResourceSelector{
ApiVersion: e.APIVersion,
Kind: e.Kind,
}

if e.MatchName == "" {
out.Match = &fnv1.ResourceSelector_MatchLabels{
MatchLabels: &fnv1.MatchLabels{Labels: e.MatchLabels},
}
} else {
out.Match = &fnv1.ResourceSelector_MatchName{
MatchName: e.MatchName,
}
}

if e.Namespace != "" {
out.Namespace = &e.Namespace
}

return out
}
```

### How can we reproduce it?

Create matching namespaced resources in two namespaces, then request them with ExtraResources using both matchLabels and namespace.
Expected result: only resources from the requested namespace.
Actual result: resources from other namespaces may be included.

### What environment did it happen in?
Function version:
xpkg.upbound.io/crossplane-contrib/function-go-templating:v0.12.0

Start in extraresources.go at ToResourceSelector(), around the referenced lines, and compare the matchLabels path with the namespace assignment. Reproduce the issue with matching namespaced resources in two namespaces; done means a request using matchLabels and namespace returns only resources from the requested namespace.

Written by the indexing model from the issue text.