Configuration system throws `PlatformNotSupportedException` on Xamarin Android.

Description

Configuration system throws PlatformNotSupportedException on Xamarin Android.

Complete minimal example reproducing the issue

3.Should().BeGreaterThan(4); // Probably any failing test?

Expected behavior:

The normal assertion failure process

Actual behavior:

The following Exception is thrown:

System.PlatformNotSupportedException : Operation is not supported on this platform.
 		  at System.Configuration.ConfigurationManager.PrepareConfigSystem () [0x0001a] in <4cd8a957e7664f4a9e27ce43dd1afeb7>:0 
 		  at System.Configuration.ConfigurationManager.GetSection (System.String sectionName) [0x0000a] in <4cd8a957e7664f4a9e27ce43dd1afeb7>:0 
 		  at System.Configuration.ConfigurationManager.get_AppSettings () [0x00000] in <4cd8a957e7664f4a9e27ce43dd1afeb7>:0 
		  at FluentAssertions.Common.AppSettingsConfigurationStore.GetSetting (System.String name) [0x00000] in <d52b982f9eb24747b8fd904dff0631fe>:0 
 		  at FluentAssertions.Common.Configuration.get_ValueFormatterAssembly () [0x00008] in <d52b982f9eb24747b8fd904dff0631fe>:0 
 		  at FluentAssertions.Common.Configuration.DetermineFormatterDetectionMode () [0x00000] in <d52b982f9eb24747b8fd904dff0631fe>:0 
 		  at FluentAssertions.Common.Configuration.get_ValueFormatterDetectionMode () [0x0001e] in <d52b982f9eb24747b8fd904dff0631fe>:0 
 		  at FluentAssertions.Formatting.AttributeBasedFormatter.get_IsScanningEnabled () [0x00005] in <d52b982f9eb24747b8fd904dff0631fe>:0 
 		  at FluentAssertions.Formatting.AttributeBasedFormatter.CanHandle (System.Object value) [0x00000] in <d52b982f9eb24747b8fd904dff0631fe>:0 
 		  at FluentAssertions.Formatting.Formatter+<>c__DisplayClass7_0.<Format>b__0 (FluentAssertions.Formatting.IValueFormatter f) [0x00000] in <d52b982f9eb24747b8fd904dff0631fe>:0 
 		  at System.Linq.Enumerable.TryGetFirst[TSource] (System.Collections.Generic.IEnumerable`1[T] source, System.Func`2[T,TResult] predicate, System.Boolean& found) [0x0003f] in <15cecf952ca44136ad5b83afa233f6f3>:0 
 		  at System.Linq.Enumerable.First[TSource] (System.Collections.Generic.IEnumerable`1[T] source, System.Func`2[T,TResult] predicate) [0x00000] in <15cecf952ca44136ad5b83afa233f6f3>:0 
 		  at FluentAssertions.Formatting.Formatter.Format (System.Object value, FluentAssertions.Formatting.FormattingContext context, FluentAssertions.Formatting.FormatChild formatChild) [0x00012] in <d52b982f9eb24747b8fd904dff0631fe>:0 
		  at FluentAssertions.Formatting.Formatter.ToString (System.Object value, System.Boolean useLineBreaks) [0x00054] in <d52b982f9eb24747b8fd904dff0631fe>:0 
 		  at FluentAssertions.Execution.MessageBuilder.<FormatArgumentPlaceholders>b__6_0 (System.Object a) [0x00000] in <d52b982f9eb24747b8fd904dff0631fe>:0 
 		  at System.Linq.Enumerable+SelectArrayIterator`2[TSource,TResult].ToArray () [0x00012] in <15cecf952ca44136ad5b83afa233f6f3>:0 
		  at System.Linq.Enumerable.ToArray[TSource] (System.Collections.Generic.IEnumerable`1[T] source) [0x0001f] in <15cecf952ca44136ad5b83afa233f6f3>:0 
 		  at FluentAssertions.Execution.MessageBuilder.FormatArgumentPlaceholders (System.String failureMessage, System.Object[] failureArgs) [0x00012] in <d52b982f9eb24747b8fd904dff0631fe>:0 
 		  at FluentAssertions.Execution.MessageBuilder.Build (System.String message, System.Object[] messageArgs, System.String reason, FluentAssertions.Execution.ContextDataItems contextData, System.String identifier, System.String fallbackIdentifier) [0x00036] in <d52b982f9eb24747b8fd904dff0631fe>:0 
 		  at FluentAssertions.Execution.AssertionScope+<>c__DisplayClass30_0.<FailWith>b__0 () [0x00055] in <d52b982f9eb24747b8fd904dff0631fe>:0 
 		  at FluentAssertions.Execution.AssertionScope.FailWith (System.Func`1[TResult] failReasonFunc) [0x0001a] in <d52b982f9eb24747b8fd904dff0631fe>:0 
 		  at FluentAssertions.Execution.AssertionScope.FailWith (System.Func`1[TResult] failReasonFunc) [0x00014] in <d52b982f9eb24747b8fd904dff0631fe>:0 
 		  at FluentAssertions.Execution.AssertionScope.FailWith (System.String message, System.Object[] args) [0x00014] in <d52b982f9eb24747b8fd904dff0631fe>:0 
 		  at FluentAssertions.Numeric.NumericAssertions`1[T].BeGreaterThan (T expected, System.String because, System.Object[] becauseArgs) [0x0004c] in <d52b982f9eb24747b8fd904dff0631fe>:0 

Versions

FluentAssertions 5.9.0 Xamarin.Android SDK 9.1.7.0 (HEAD/ba9da7a76) Emulator 27.3.9-4899998 API 27 (x86)

[borrrden]

I imagine it compiles because of the odd Microsoft policy that it is acceptable for things to be part of the .NET Standard, but then throw not supported exceptions on platforms that are not applicable…

[jnyrup]

Fixed in #1210, which is included in 5.10.0