Enable JSON language injection

So that your Integrated Development Environment (IDE) can perform nice syntax highlighting.

See [Language injections in C#][1] in Rider for example.

Also remove some trailing commas that were highlighted after adding the // language=json comment

[1]: https://www.jetbrains.com/help/rider/Language_Injections.html

Author: 0xced

test/Serilog.Settings.Configuration.Tests/ConfigurationReaderTests.cs

@@ -23,6 +23,7 @@ public ConfigurationReaderTests()
     [Fact]
     public void WriteToSupportSimplifiedSyntax()
     {
+        // language=json
         var json = """
         {
             "WriteTo": [ "LiterateConsole", "DiagnosticTrace" ]
@@ -41,6 +42,7 @@ public void WriteToSupportSimplifiedSyntax()
     [Fact]
     public void WriteToSupportExpandedSyntaxWithoutArgs()
     {
+        // language=json
         var json = """
         {
             "WriteTo": [ {
@@ -59,13 +61,14 @@ public void WriteToSupportExpandedSyntaxWithoutArgs()
     [Fact]
     public void WriteToSupportExpandedSyntaxWithArgs()
     {
+        // language=json
         var json = """
         {
             "WriteTo": [ {
                 "Name": "LiterateConsole",
                 "Args": {
                     "outputTemplate": "{Message}"
-                },
+                }
             }]
         }
         """;
@@ -87,28 +90,29 @@ public void WriteToSupportExpandedSyntaxWithArgs()
     [Fact]
     public void WriteToSupportMultipleSinksOfTheSameKind()
     {
+        // language=json
         var json = """
         {
             "WriteTo": [
               {
                 "Name": "LiterateConsole",
                 "Args": {
                     "outputTemplate": "{Message}"
-                  },
+                  }
               },
               "DiagnosticTrace"
             ],
             "WriteTo:File1": {
                 "Name": "File",
                 "Args": {
                     "outputTemplate": "{Message}"
-                },
+                }
             },
             "WriteTo:File2": {
                 "Name": "File",
                 "Args": {
                     "outputTemplate": "{Message}"
-                },
+                }
             }
         }
         """;
@@ -128,6 +132,7 @@ public void WriteToSupportMultipleSinksOfTheSameKind()
     [Fact]
     public void Enrich_SupportSimplifiedSyntax()
     {
+        // language=json
         var json = """
         {
             "Enrich": [ "FromLogContext", "WithMachineName", "WithThreadId" ]
@@ -273,6 +278,7 @@ public void MixedMinimumLevelCorrectOneIsEnabledOnLogger(IConfigurationRoot root
     [Fact]
     public void NoConfigurationRootUsedStillValid()
     {
+        // language=json
         var json = """
         {
             "Nest": {