Reimplement archetypes

The old implementation had some issues, mostly related to the context (e.g. name, file paths) passed to the template.

This new implementation is using the exact same code path for evaluating the pages as in a regular build.

This also makes it more robust and easier to reason about in a multilingual setup.

Now, if you are explicit about the target path, Hugo will now always pick the correct mount and language:

```bash
hugo new content/en/posts/my-first-post.md
```

Fixes gohugoio#9032
Fixes gohugoio#7589
Fixes gohugoio#9043
Fixes gohugoio#9046
Fixes gohugoio#9047

commands/hugo.go

@@ -870,7 +870,7 @@ func (c *commandeer) newWatcher(pollIntervalStr string, dirList ...string) (*wat
 					livereload.ForceRefresh()
 				}
 			case err := <-watcher.Errors():
-				if err != nil {
+				if err != nil && !os.IsNotExist(err) {
 					c.logger.Errorln("Error while watching:", err)
 				}
 			}

commands/new.go

@@ -80,17 +80,7 @@ func (n *newCmd) newContent(cmd *cobra.Command, args []string) error {
 		return newUserError("path needs to be provided")
 	}
 
-	createPath := args[0]
-
-	var kind string
-
-	createPath, kind = newContentPathSection(c.hugo(), createPath)
-
-	if n.contentType != "" {
-		kind = n.contentType
-	}
-
-	return create.NewContent(c.hugo(), kind, createPath)
+	return create.NewContent(c.hugo(), n.contentType, args[0])
 }
 
 func mkdir(x ...string) {

commands/new_site.go

@@ -102,7 +102,7 @@ func (n *newSiteCmd) doNewSite(fs *hugofs.Fs, basepath string, force bool) error
 
 	// Create a default archetype file.
 	helpers.SafeWriteToDisk(filepath.Join(archeTypePath, "default.md"),
-		strings.NewReader(create.ArchetypeTemplateTemplate), fs.Source)
+		strings.NewReader(create.DefaultArchetypeTemplateTemplate), fs.Source)
 
 	jww.FEEDBACK.Printf("Congratulations! Your new Hugo site is created in %s.\n\n", basepath)
 	jww.FEEDBACK.Println(nextStepsText())