feat(sdk): auto-include imagemanifest and ContentManifest.json files (#33)

- Add ImageManifest item auto-include for .imagemanifest files
- Add Content item auto-include for ContentManifest.json files
- Both can be disabled with EnableDefault*Items=false properties

Closes #31

Author: CalvinAllen

src/CodingWithCalvin.VsixSdk/Sdk/Sdk.Vsix.targets

@@ -34,6 +34,21 @@
       <DependentUpon>VSPackage.resx</DependentUpon>
     </EmbeddedResource>
 
+    <!-- Include Image Manifest files for VS Image Service -->
+    <ImageManifest Include="**/*.imagemanifest"
+                   Condition="'$(EnableDefaultImageManifestItems)' != 'false'"
+                   Exclude="$(DefaultItemExcludes);$(DefaultExcludesInProjectFolder)">
+      <IncludeInVSIX>true</IncludeInVSIX>
+    </ImageManifest>
+
+    <!-- Include Content Manifest files -->
+    <Content Include="**/ContentManifest.json"
+             Condition="'$(EnableDefaultContentManifestItems)' != 'false'"
+             Exclude="$(DefaultItemExcludes);$(DefaultExcludesInProjectFolder)">
+      <IncludeInVSIX>true</IncludeInVSIX>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+
   </ItemGroup>
 
   <PropertyGroup>