Reorgranised blade view files to form a convention

- Primarily moved and re-organised view files.
- Included readme within views to document the convention.
- Fixed some issues with page field select list in previous commit.
- Tweaked some route names while going through.
- Split some views out further.

Closes #2805

app/Entities/Tools/PageContent.php

@@ -223,7 +223,7 @@ class PageContent
      */
     public function render(bool $blankIncludes = false): string
     {
-        $content = $this->page->html;
+        $content = $this->page->html ?? '';
 
         if (!config('app.allow_content_scripts')) {
             $content = HtmlContentFilter::removeScripts($content);