Move SearchQueryFilterClause to Plugins.Web and make FilterClause constructor public

Per reviewer feedback, moving SearchQueryFilterClause from Microsoft.Extensions.VectorData to Microsoft.SemanticKernel.Plugins.Web namespace as internal class, where it's actually used (Brave/Tavily connectors).

Changes:
- FilterClause.cs: Changed constructor from 'internal' to 'public' to allow external inheritance
- SearchQueryFilterClause.cs: Moved to Plugins.Web/FilterClauses/ as internal sealed class
- VectorData.Abstractions.csproj: Added CA1012 suppression (abstract types with public constructors)

Trade-off: Opening FilterClause to external inheritance is accepted to minimize MEVD public API surface.

Author: alzarei

dotnet/src/VectorData/VectorData.Abstractions/FilterClauses/SearchQueryFilterClause.cs renamed to dotnet/src/Plugins/Plugins.Web/FilterClauses/SearchQueryFilterClause.cs

@@ -1,6 +1,8 @@
 // Copyright (c) Microsoft. All rights reserved.
 
-namespace Microsoft.Extensions.VectorData;
+using Microsoft.Extensions.VectorData;
+
+namespace Microsoft.SemanticKernel.Plugins.Web;
 
 /// <summary>
 /// Represents a filter clause that adds terms to the search query itself for text search engines.
@@ -18,7 +20,7 @@ namespace Microsoft.Extensions.VectorData;
 ///
 /// See ADR-TextSearch-Contains-Support.md for architectural context and cross-engine comparison.
 /// </remarks>
-public sealed class SearchQueryFilterClause : FilterClause
+internal sealed class SearchQueryFilterClause : FilterClause
 {
     /// <summary>
     /// Initializes a new instance of the <see cref="SearchQueryFilterClause"/> class.

dotnet/src/VectorData/VectorData.Abstractions/FilterClauses/FilterClause.cs

@@ -11,7 +11,10 @@ namespace Microsoft.Extensions.VectorData;
 /// </remarks>
 public abstract class FilterClause
 {
-    internal FilterClause()
+    /// <summary>
+    /// Initializes a new instance of the <see cref="FilterClause"/> class.
+    /// </summary>
+    public FilterClause()
     {
     }
 }

dotnet/src/VectorData/VectorData.Abstractions/VectorData.Abstractions.csproj

@@ -7,6 +7,8 @@
     <IsAotCompatible Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0'))">true</IsAotCompatible>
     <!-- temporarily disabled due to mysterious build issue -->
     <EnablePackageValidation>false</EnablePackageValidation>
+    <!-- Suppress CA1012: FilterClause constructor made public to allow Plugins.Web to inherit -->
+    <NoWarn>$(NoWarn);CA1012</NoWarn>
   </PropertyGroup>
 
   <Import Project="$(RepoRoot)/dotnet/nuget/nuget-package.props" />