common/hugo: Add hugo.IsServer and hugo.IsDevelopment

And deprecate site.IsServer.

Closes #11510

resources/page/page_matcher_test.go

@@ -159,6 +159,7 @@ func TestDecodeCascadeConfig(t *testing.T) {
 
 type testConfig struct {
 	environment string
+	running     bool
 	workingDir  string
 }
 
@@ -166,6 +167,10 @@ func (c testConfig) Environment() string {
 	return c.environment
 }
 
+func (c testConfig) Running() bool {
+	return c.running
+}
+
 func (c testConfig) WorkingDir() string {
 	return c.workingDir
 }