Add channel test providers for Email, Slack, Teams, and Webhook

- Implemented EmailChannelTestProvider to generate email preview payloads.
- Implemented SlackChannelTestProvider to create Slack message previews.
- Implemented TeamsChannelTestProvider for generating Teams Adaptive Card previews.
- Implemented WebhookChannelTestProvider to create webhook payloads.
- Added INotifyChannelTestProvider interface for channel-specific preview generation.
- Created ChannelTestPreviewContracts for request and response models.
- Developed NotifyChannelTestService to handle test send requests and generate previews.
- Added rate limit policies for test sends and delivery history.
- Implemented unit tests for service registration and binding.
- Updated project files to include necessary dependencies and configurations.

src/Directory.Build.props

@@ -1,9 +1,9 @@
 <Project>
   <PropertyGroup>
-    <ConcelierPluginOutputRoot Condition="'$(ConcelierPluginOutputRoot)' == ''">$(SolutionDir)PluginBinaries</ConcelierPluginOutputRoot>
-    <ConcelierPluginOutputRoot Condition="'$(ConcelierPluginOutputRoot)' == '' and '$(SolutionDir)' == ''">$(MSBuildThisFileDirectory)PluginBinaries</ConcelierPluginOutputRoot>
-    <AuthorityPluginOutputRoot Condition="'$(AuthorityPluginOutputRoot)' == ''">$(SolutionDir)PluginBinaries\Authority</AuthorityPluginOutputRoot>
-    <AuthorityPluginOutputRoot Condition="'$(AuthorityPluginOutputRoot)' == '' and '$(SolutionDir)' == ''">$(MSBuildThisFileDirectory)PluginBinaries\Authority</AuthorityPluginOutputRoot>
+    <ConcelierPluginOutputRoot Condition="'$(ConcelierPluginOutputRoot)' == ''">$(SolutionDir)StellaOps.Concelier.PluginBinaries</ConcelierPluginOutputRoot>
+    <ConcelierPluginOutputRoot Condition="'$(ConcelierPluginOutputRoot)' == '' and '$(SolutionDir)' == ''">$(MSBuildThisFileDirectory)StellaOps.Concelier.PluginBinaries</ConcelierPluginOutputRoot>
+    <AuthorityPluginOutputRoot Condition="'$(AuthorityPluginOutputRoot)' == ''">$(SolutionDir)StellaOps.Authority.PluginBinaries</AuthorityPluginOutputRoot>
+    <AuthorityPluginOutputRoot Condition="'$(AuthorityPluginOutputRoot)' == '' and '$(SolutionDir)' == ''">$(MSBuildThisFileDirectory)StellaOps.Authority.PluginBinaries</AuthorityPluginOutputRoot>
     <IsConcelierPlugin Condition="'$(IsConcelierPlugin)' == '' and $([System.String]::Copy('$(MSBuildProjectName)').StartsWith('StellaOps.Concelier.Connector.'))">true</IsConcelierPlugin>
     <IsConcelierPlugin Condition="'$(IsConcelierPlugin)' == '' and $([System.String]::Copy('$(MSBuildProjectName)').StartsWith('StellaOps.Concelier.Exporter.'))">true</IsConcelierPlugin>
     <IsAuthorityPlugin Condition="'$(IsAuthorityPlugin)' == '' and $([System.String]::Copy('$(MSBuildProjectName)').StartsWith('StellaOps.Authority.Plugin.'))">true</IsAuthorityPlugin>
@@ -20,12 +20,17 @@
     <ProjectReference Update="../StellaOps.Plugin/StellaOps.Plugin.csproj">
       <Private>false</Private>
       <ExcludeAssets>runtime</ExcludeAssets>
-    </ProjectReference>
-  </ItemGroup>
-
+    </ProjectReference>
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Update="MongoDB.Driver" Version="3.5.0" />
+    <PackageReference Include="SharpCompress" Version="0.41.0" />
+  </ItemGroup>
+
   <ItemGroup Condition="$([System.String]::Copy('$(MSBuildProjectName)').EndsWith('.Tests')) and '$(UseConcelierTestInfra)' != 'false'">
-    <PackageReference Include="coverlet.collector" Version="6.0.4" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.0" />
+    <PackageReference Include="coverlet.collector" Version="6.0.4" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.0" />
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="8.0.8" />
     <PackageReference Include="Mongo2Go" Version="4.1.0" />
     <PackageReference Include="xunit" Version="2.9.2" />