Add VS2019 support

Author: Pzixel

Solidity/Solidity.ProjectType/source.extension.vsixmanifest

@@ -6,7 +6,9 @@
         <Description xml:space="preserve">A template for creating a Solidity project.</Description>
     </Metadata>
     <Installation>
-        <InstallationTarget Id="Microsoft.VisualStudio.Pro" Version="15.0" />
+        <InstallationTarget Id="Microsoft.VisualStudio.Pro" Version="[15.0,]" />
+        <InstallationTarget Id="Microsoft.VisualStudio.Community" Version="[15.0,]" />
+        <InstallationTarget Id="Microsoft.VisualStudio.Enterprise" Version="[15.0,]" />
     </Installation>
     <Dependencies>
         <!--<Dependency Id="Microsoft.Framework.NDP" DisplayName="Microsoft .NET Framework" d:Source="Manual" Version="4.6" />-->