Update to dotnet 8 preview 5 (#14492)

* Update to .net 8 preview 1

* Update npoco to 5.7.0

* Update pipeline to use .net 8

* Revert "Update npoco to 5.7.0"

This reverts commit f7795afa77a41ef2719f639405f73d9c21e4b12e.

* Fix tests and updated OpenApi.json

* use dotnet 8 in linux container

* Updated templates and docker image to dotnet 8

* Bugfix

* R
Updated docker images to 8.0 preview 1

* linux docker images updated

* Force use c# 11, in hope of the acceptance tests will pass

* Do not use C# 8 :)

* Update to preview 2

* CompatibilitySuppressions

* updated templates

* Disable package validation

* Update to .net8 preview 4

* change EnableStrictModeForCompatibleFrameworksInPackage to false

* Package validation

* Added CompatibilitySuppressions.xml

* Fix up IP networks

* Updated to preview 5

* Update docker images

* Post merge fixes

* Try to update dotnet version of codeql

* Delete empty suppression files

* Remove dependency

* Cleanup

---------

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

templates/UmbracoProject/.template.config/template.json

@@ -38,13 +38,13 @@
       "datatype": "choice",
       "choices": [
         {
-          "displayName": ".NET 7.0",
-          "description": "Target net7.0",
-          "choice": "net7.0"
+          "displayName": ".NET 8.0",
+          "description": "Target net8.0",
+          "choice": "net8.0"
         }
       ],
-      "defaultValue": "net7.0",
-      "replaces": "net7.0"
+      "defaultValue": "net8.0",
+      "replaces": "net8.0"
     },
     "UmbracoVersion": {
       "displayName": "Umbraco version",