refactor: Make SearchQueryFilterClause public (revert internal approach)

Reverting the internal + InternalsVisibleTo approach per reviewer feedback.
Making SearchQueryFilterClause public is the cleanest solution:

- Legitimate, reusable abstraction for text search scenarios
- Respects FilterClause architecture (stays in VectorData.Abstractions)
- No InternalsVisibleTo complexity or CS0436 warnings
- Precedent: Other FilterClause types are public (EqualToFilterClause, etc.)
- Other search connectors can benefit from this pattern

Trade-off: Adds one class to VectorData.Abstractions public API surface,
but it's a well-scoped, documented filter clause pattern with clear use cases.

Addresses reviewer question about SearchQueryFilterClause visibility.

Author: alzarei

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

@@ -18,7 +18,7 @@ namespace Microsoft.Extensions.VectorData;
 ///
 /// See ADR-TextSearch-Contains-Support.md for architectural context and cross-engine comparison.
 /// </remarks>
-internal sealed class SearchQueryFilterClause : FilterClause
+public sealed class SearchQueryFilterClause : FilterClause
 {
     /// <summary>
     /// Initializes a new instance of the <see cref="SearchQueryFilterClause"/> class.

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

@@ -36,10 +36,6 @@ Microsoft.Extensions.VectorData.IVectorStoreRecordCollection<TKey, TRecord&gt
     <PackageReference Include="Microsoft.Extensions.AI.Abstractions" />
   </ItemGroup>
 
-  <ItemGroup>
-    <InternalsVisibleTo Include="Microsoft.SemanticKernel.Plugins.Web" />
-  </ItemGroup>
-
   <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' Or '$(TargetFramework)' == 'net462' ">
     <PackageReference Include="Microsoft.Bcl.AsyncInterfaces" />
     <PackageReference Include="System.Text.Json" />