chore: add package assets and metadata

Include default packaging assets at the build props level so projects without local copies will include a readme, license and icon in produced packages.
Add a project package description and broaden package tags to improve discoverability.
Add the binary icon asset.

Ensure consistent packaged contents and better metadata for consumers.

Author: SakuraIsayeki

Directory.Build.props

@@ -9,5 +9,12 @@
   <ItemGroup Condition="$(PackAsTool) != 'true'">
     <PackageReference Include="DotNet.ReproducibleBuilds" Version="1.2.39" PrivateAssets="All"/>
   </ItemGroup>
+
+  <ItemGroup Label="PackageInfoFiles">
+    <!-- Import the Readme at build props level if there is none in the project -->
+    <None Condition="!Exists('README.md')" Include="$(_DirectoryBuildPropsBasePath)\README.md" Pack="true" PackagePath="/" />
+    <None Include="$(MSBuildThisFileDirectory)\LICENSE" Pack="true" PackagePath="/" />
+    <None Include="$(MSBuildThisFileDirectory)\icon.png" Pack="true" PackagePath="/" />
+  </ItemGroup>
 
 </Project>

YumeChan.RoleDeck.csproj

@@ -5,14 +5,15 @@
     <Authors>Sakura Akeno Isayeki</Authors>
     <Company>Nodsoft Systems</Company>
     <Product>RoleDeck</Product>
+    <Description>Roles management plugin for Yume-Chan</Description>
     <RepositoryType>git</RepositoryType>
     <RepositoryUrl>https://github.com/YumeChan-DT/RoleDeck</RepositoryUrl>
 
     <OutDir>$(YumeChan_PluginsLocation)</OutDir>
     <OutputPath>$(YumeChan_PluginsLocation)</OutputPath>
     <Copyright>GNU-GPLv3</Copyright>
 
-    <PackageTags>yumechan,plugin</PackageTags>
+    <PackageTags>discord,yumechan,plugin,roles,permissions</PackageTags>
   </PropertyGroup>
 
   <ItemGroup>