hugofs: Make FileMeta a struct

This commit started out investigating a `concurrent map read write` issue, ending by replacing the map with a struct.

This is easier to reason about, and it's more effective:

```
name                                  old time/op    new time/op    delta
SiteNew/Regular_Deep_content_tree-16    71.5ms ± 3%    69.4ms ± 5%    ~     (p=0.200 n=4+4)

name                                  old alloc/op   new alloc/op   delta
SiteNew/Regular_Deep_content_tree-16    29.7MB ± 0%    27.9MB ± 0%  -5.82%  (p=0.029 n=4+4)

name                                  old allocs/op  new allocs/op  delta
SiteNew/Regular_Deep_content_tree-16      313k ± 0%      303k ± 0%  -3.35%  (p=0.029 n=4+4)
```

See #8749

1 files changed, 7 insertions, 7 deletions

diff --git a/create/content.go b/create/content.go
index 797ffe758..ea065423e 100644
--- a/create/content.go
+++ b/create/content.go
@@ -123,7 +123,7 @@ func NewContent(
 
 func targetSite(sites *hugolib.HugoSites, fi hugofs.FileMetaInfo) *hugolib.Site {
 	for _, s := range sites.Sites {
-		if fi.Meta().Lang() == s.Language().Lang {
+		if fi.Meta().Lang == s.Language().Lang {
 			return s
 		}
 	}
@@ -137,7 +137,7 @@ func newContentFromDir(
 	cm archetypeMap, name, targetPath string) error {
 	for _, f := range cm.otherFiles {
 		meta := f.Meta()
-		filename := meta.Path()
+		filename := meta.Path
 		// Just copy the file to destination.
 		in, err := meta.Open()
 		if err != nil {
@@ -166,7 +166,7 @@ func newContentFromDir(
 	}
 
 	for _, f := range cm.contentFiles {
-		filename := f.Meta().Path()
+		filename := f.Meta().Path
 		s := targetSite(sites, f)
 		targetFilename := filepath.Join(targetPath, strings.TrimPrefix(filename, archetypeDir))
 
@@ -274,7 +274,7 @@ func resolveContentPath(sites *hugolib.HugoSites, fs afero.Fs, targetPath string
 
 	for _, dir := range sites.BaseFs.Content.Dirs {
 		meta := dir.Meta()
-		contentDir := meta.Filename()
+		contentDir := meta.Filename
 
 		if !strings.HasSuffix(contentDir, helpers.FilePathSeparator) {
 			contentDir += helpers.FilePathSeparator
@@ -282,7 +282,7 @@ func resolveContentPath(sites *hugolib.HugoSites, fs afero.Fs, targetPath string
 
 		if strings.HasPrefix(targetPath, contentDir) {
 			siteContentDir = contentDir
-			dirLang = meta.Lang()
+			dirLang = meta.Lang
 			break
 		}
 	}
@@ -317,8 +317,8 @@ func resolveContentPath(sites *hugolib.HugoSites, fs afero.Fs, targetPath string
 	} else {
 		var contentDir string
 		for _, dir := range sites.BaseFs.Content.Dirs {
-			contentDir = dir.Meta().Filename()
-			if dir.Meta().Lang() == s.Lang() {
+			contentDir = dir.Meta().Filename
+			if dir.Meta().Lang == s.Lang() {
 				break
 			}
 		}