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

minifiers/config.go

@@ -15,7 +15,6 @@ package minifiers
 
 import (
 	"github.com/gohugoio/hugo/common/maps"
-	"github.com/gohugoio/hugo/config"
 	"github.com/gohugoio/hugo/docshelper"
 	"github.com/gohugoio/hugo/parser"
 	"github.com/spf13/cast"
@@ -29,7 +28,7 @@ import (
 	"github.com/tdewolff/minify/v2/xml"
 )
 
-var defaultTdewolffConfig = tdewolffConfig{
+var defaultTdewolffConfig = TdewolffConfig{
 	HTML: html.Minifier{
 		KeepDocumentTags:        true,
 		KeepConditionalComments: true,
@@ -52,7 +51,7 @@ var defaultTdewolffConfig = tdewolffConfig{
 	},
 }
 
-type tdewolffConfig struct {
+type TdewolffConfig struct {
 	HTML html.Minifier
 	CSS  css.Minifier
 	JS   js.Minifier
@@ -61,7 +60,7 @@ type tdewolffConfig struct {
 	XML  xml.Minifier
 }
 
-type minifyConfig struct {
+type MinifyConfig struct {
 	// Whether to minify the published output (the HTML written to /public).
 	MinifyOutput bool
 
@@ -72,30 +71,20 @@ type minifyConfig struct {
 	DisableSVG  bool
 	DisableXML  bool
 
-	Tdewolff tdewolffConfig
+	Tdewolff TdewolffConfig
 }
 
-var defaultConfig = minifyConfig{
+var defaultConfig = MinifyConfig{
 	Tdewolff: defaultTdewolffConfig,
 }
 
-func decodeConfig(cfg config.Provider) (conf minifyConfig, err error) {
+func DecodeConfig(v any) (conf MinifyConfig, err error) {
 	conf = defaultConfig
 
-	// May be set by CLI.
-	conf.MinifyOutput = cfg.GetBool("minifyOutput")
-
-	v := cfg.Get("minify")
 	if v == nil {
 		return
 	}
 
-	// Legacy.
-	if b, ok := v.(bool); ok {
-		conf.MinifyOutput = b
-		return
-	}
-
 	m := maps.ToStringMap(v)
 
 	// Handle upstream renames.