NuGet vulnerability warnings: Warn in non-Release mode, Error in non-Release mode (#17244)

* Initial adjustment of the projects with package vulnerabilities that errored, to change to ignore the four specific Nuget vulnerability warnings in Debug mode (but not Release) as per https://learn.microsoft.com/en-us/nuget/reference/errors-and-warnings/nu1901-nu1904 (NU1901,NU1902,NU1903,NU1904)

* Fixed formatting errors with tests

* No trailing whitespace

* Move NuGet vulnerability warnings error suppression to Directory.Build.props, combine WarningsNotAsErrors and fix minor issues

* Update Umbraco.JsonSchema.csproj

Removed unwanted change

* Update Umbraco.JsonSchema.csproj

Removed unwanted change

* Revert unecessary changes since merge

* Tweak more unecessary changes

* Small tweaks

* Remove space

* Reverted spacing changes

* Remove no longer required warning exclusions

* Reverted unwanted change

* Reversed order

* A few tweaks to reduce warnings in Umbraco.TestData

* More warnings removed as no longer an issue

---------

Co-authored-by: Ronald Barendse <ronald@barend.se>
Co-authored-by: Emma Garland <emma.garland@rocksolidknowledge.com>
Co-authored-by: Jason Elkin <jasonelkin86@gmail.com>

src/Umbraco.Core/Umbraco.Core.csproj

@@ -16,7 +16,7 @@
       [CS0618]/[CS0672]/[SYSLIB0051]/[SYSLIB0044]/[SYSLIB0023]/[SYSLIB0003]/[SYSLIB0045] adjust obsolete references
       [CS0067] unused event
       [SA1405] debug provide message text
-      [CS0168]/[CS0169] unused fields/variables
+      [CS0168] and [CS0169] unused fields/variables
       [CS0183] always of type
       [SA1111] adjust parenthesis
       [CA2017] match parameters number