Ensure package view path is generated with consideration the current section (#14268)

* check section when determining package template path

* return sectionAlias as packageFolder and the route segment won't always match

* fix test

* adds PluginController attribute to StylesheetsTreeController
fixes actionUrl generation to ensure valid URL
find controller by fullname to avoid incorrect controller selection when multiple exist with same name

* Fix frontend breaking changes

* Adding missing PluginController attribute for ScriptsTreeController

---------

Co-authored-by: Elitsa <elm@umbraco.dk>

src/Umbraco.Web.BackOffice/Controllers/BackOfficeServerVariables.cs

@@ -704,6 +704,9 @@ namespace Umbraco.Cms.Web.BackOffice.Controllers
 
             [DataMember(Name = "packageFolder")]
             public string? PackageFolder { get; set; }
+
+            [DataMember(Name = "sectionAlias")]
+            public string? SectionAlias { get; set; }
         }
 
         private IEnumerable<PluginTree> GetPluginTrees()
@@ -735,7 +738,7 @@ namespace Umbraco.Cms.Web.BackOffice.Controllers
                     continue;
                 }
 
-                yield return new PluginTree { Alias = tree.TreeAlias, PackageFolder = pluginController.AreaName };
+                yield return new PluginTree { Alias = tree.TreeAlias, PackageFolder = pluginController.AreaName, SectionAlias = tree.SectionAlias };
             }
         }