message: Add remaining signus tests.
diff: <Compile Include="Wrapper\PoolTests\RefreshPoolTest.cs" />
  <Compile Include="Wrapper\PoolTests\OpenPoolTest.cs" />
  <Compile Include="Wrapper\PoolTests\DeletePoolTest.cs" />
  + <Compile Include="Wrapper\SignusTests\VerifyTest.cs" />
  + <Compile Include="Wrapper\SignusTests\StoreTheirDidTest.cs" />
  <Compile Include="Wrapper\SignusTests\SignTest.cs" />
  <Compile Include="Wrapper\SignusTests\ReplaceKeysTest.cs" />
  <Compile Include="Wrapper\SignusTests\CreateMyDidTest.cs" />
  