Simplify JSON schema, generation, copying and updating (#13427)

* Simplify JSON schema and only generate appsettings-schema.Umbraco.Cms.json

* Use Umbraco.JsonSchema.Extensions to dynamically add JSON schema references

* Move DependentUpon items to shared MSBuild props

* Update LangVersion to latest

* Update Umbraco.GitVersioning.Extensions to 0.2.0

* Remove JSON schemas on clean

* Remove Umbraco.JsonSchema.Core project

* Fix JSON schema nullability

* Ignore additional JSON schema files in template

* Update CompatibilitySuppressions.xml

* Remove GlobalSettings.UmbracoPath from JSON schema again

* Remove RemoveUmbracoJsonSchemaFiles target

* Update Umbraco.JsonSchema.Extensions to 0.2.0 and add weights

* Flatten generated JSON schema hierarchy

* Remove LicensesSettings from CMS codebase

* Change AdditionalParameters to IDictionary

tools/Umbraco.JsonSchema/UmbracoJsonSchemaGenerator.cs

@@ -0,0 +1,35 @@
+using Newtonsoft.Json;
+using Newtonsoft.Json.Converters;
+using Newtonsoft.Json.Serialization;
+using NJsonSchema.Generation;
+
+/// <inheritdoc />
+public class UmbracoJsonSchemaGenerator : JsonSchemaGenerator
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="UmbracoJsonSchemaGenerator" /> class.
+    /// </summary>
+    public UmbracoJsonSchemaGenerator()
+        : base(new JsonSchemaGeneratorSettings()
+        {
+            AlwaysAllowAdditionalObjectProperties = true,
+            DefaultReferenceTypeNullHandling = ReferenceTypeNullHandling.NotNull,
+            FlattenInheritanceHierarchy = true,
+            IgnoreObsoleteProperties = true,
+            SerializerSettings = new JsonSerializerSettings()
+            {
+                ContractResolver = new WritablePropertiesOnlyResolver()
+            }
+        })
+    {
+        Settings.SerializerSettings.Converters.Add(new StringEnumConverter());
+    }
+
+    /// <inheritdoc />
+    private class WritablePropertiesOnlyResolver : DefaultContractResolver
+    {
+        /// <inheritdoc />
+        protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
+            => base.CreateProperties(type, memberSerialization).Where(p => p.Writable).ToList();
+    }
+}