SQL Expressions: Add endpoint to get Schemas (#108864)

Return the SQL schema for all DS queries in request (to provide information to AI / Autocomplete for SQL expressions).

All DS queries are treated as if they were inputs to SQL expressions in terms of conversion, regardless if they are selected in a query or not.

Requires feature toggle queryService = true

Endpoint is apis/query.grafana.app/v0alpha1/namespaces/default/sqlschemas

---------

Co-authored-by: Todd Treece <360020+toddtreece@users.noreply.github.com>

pkg/apis/query/v0alpha1/zz_generated.deepcopy.go

@@ -262,3 +262,29 @@ func (in *QueryTypeDefinitionList) DeepCopyObject() runtime.Object {
 	}
 	return nil
 }
+
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *SQLSchemas) DeepCopyInto(out *SQLSchemas) {
+	*out = *in
+	out.TypeMeta = in.TypeMeta
+	out.SQLSchemas = in.SQLSchemas.DeepCopy()
+	return
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new SQLSchemas.
+func (in *SQLSchemas) DeepCopy() *SQLSchemas {
+	if in == nil {
+		return nil
+	}
+	out := new(SQLSchemas)
+	in.DeepCopyInto(out)
+	return out
+}
+
+// DeepCopyObject is an autogenerated deepcopy function, copying the receiver, creating a new runtime.Object.
+func (in *SQLSchemas) DeepCopyObject() runtime.Object {
+	if c := in.DeepCopy(); c != nil {
+		return c
+	}
+	return nil
+}