Add '.Signed' suffix to assembly name of signed projects

When upgrading to .NET Core SDK 2.x it consistently errored on
"missing project info" when trying to build
UnitsNet.Serialization.JsonNet.Signed project.
This may have been a hidden error all along, but it semes it incorrectly
tried to reference the unsigned UnitsNet.dll because UnitsNet dlls shared
assembly name (and file name). This was previously ok because they
used different "obj" folders, but the new .NET Core SDK version gave warning
on the use of BaseIntermediateOutputPath and probably looked up the wrong
folder.

Author: angularsen

UnitsNet.Serialization.JsonNet/UnitsNet.Serialization.JsonNet.Signed.csproj

@@ -12,6 +12,7 @@
     <DefineConstants>SIGNED</DefineConstants>
     <SignAssembly>true</SignAssembly>
     <AssemblyOriginatorKeyFile>$(MSBuildProjectDirectory)\..\UnitsNet.snk</AssemblyOriginatorKeyFile>
+    <AssemblyName>UnitsNet.Serialization.JsonNet.Signed</AssemblyName>
   </PropertyGroup>
 
   <!-- Signed project references, will also generate the corresponding nuget dependencies -->

UnitsNet/UnitsNet.NetStandard10.Signed.csproj

@@ -12,6 +12,7 @@
     <DefineConstants>SIGNED</DefineConstants>
     <SignAssembly>true</SignAssembly>
     <AssemblyOriginatorKeyFile>$(MSBuildProjectDirectory)\..\UnitsNet.snk</AssemblyOriginatorKeyFile>
+    <AssemblyName>UnitsNet.Signed</AssemblyName>
   </PropertyGroup>
 
 </Project>