Create a struct with all of Hugo's config options

Primary motivation is documentation, but it will also hopefully simplify the code.

Also,

* Lower case the default output format names; this is in line with the custom ones (map keys) and how
it's treated all the places. This avoids doing `stringds.EqualFold` everywhere.

Closes #10896
Closes #10620

resources/page/testhelpers_page_test.go

@@ -0,0 +1,38 @@
+// Copyright 2023 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package page_test
+
+import (
+	"github.com/gohugoio/hugo/common/loggers"
+	"github.com/gohugoio/hugo/config"
+	"github.com/gohugoio/hugo/config/testconfig"
+	"github.com/gohugoio/hugo/helpers"
+	"github.com/gohugoio/hugo/hugofs"
+	"github.com/spf13/afero"
+)
+
+func newTestPathSpec() *helpers.PathSpec {
+	return newTestPathSpecFor(config.New())
+}
+
+func newTestPathSpecFor(cfg config.Provider) *helpers.PathSpec {
+	mfs := afero.NewMemMapFs()
+	conf := testconfig.GetTestConfig(mfs, cfg)
+	fs := hugofs.NewFrom(mfs, conf.BaseConfig())
+	ps, err := helpers.NewPathSpec(fs, conf, loggers.NewErrorLogger())
+	if err != nil {
+		panic(err)
+	}
+	return ps
+}