Set $(IsTestProject)

This disables the `BannedApisAnalyzer` in these projects.

Test projects are fine to use "banned" APIs.

Author: jonathanpeppers

src/Controls/tests/DeviceTests/Controls.DeviceTests.csproj

@@ -7,6 +7,7 @@
     <RootNamespace>Microsoft.Maui.DeviceTests</RootNamespace>
     <AssemblyName>Microsoft.Maui.Controls.DeviceTests</AssemblyName>
     <NoWarn>$(NoWarn),CA1416</NoWarn>
+    <IsTestProject>true</IsTestProject>
     <ExcludeMicrosoftNetTestSdk>true</ExcludeMicrosoftNetTestSdk>
     <!-- Disable multi-RID builds to workaround a parallel build issue -->
     <RuntimeIdentifier Condition="$(TargetFramework.Contains('-maccatalyst'))">maccatalyst-x64</RuntimeIdentifier>

src/Core/tests/DeviceTests/Core.DeviceTests.csproj

@@ -7,6 +7,7 @@
     <RootNamespace>Microsoft.Maui.DeviceTests</RootNamespace>
     <AssemblyName>Microsoft.Maui.Core.DeviceTests</AssemblyName>
     <NoWarn>$(NoWarn),CA1416</NoWarn>
+    <IsTestProject>true</IsTestProject>
     <!-- Disable multi-RID builds to workaround a parallel build issue -->
     <RuntimeIdentifier Condition="$(TargetFramework.Contains('-maccatalyst'))">maccatalyst-x64</RuntimeIdentifier>
     <RuntimeIdentifier Condition="$(TargetFramework.Contains('-maccatalyst')) and '$([System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture)' == 'arm64'">maccatalyst-arm64</RuntimeIdentifier>