Moved search files to abstractions and infrastructure

src/Umbraco.Infrastructure/Search/SearchableTreeCollection.cs

@@ -1,10 +1,8 @@
 using System;
 using System.Collections.Generic;
-using System.Collections.ObjectModel;
 using System.Linq;
 using Umbraco.Core;
 using Umbraco.Core.Composing;
-using Umbraco.Core.Services;
 using Umbraco.Web.Services;
 using Umbraco.Web.Trees;
 

src/Umbraco.Web/Umbraco.Web.csproj

@@ -366,10 +366,6 @@
     <Compile Include="Routing\IContentLastChanceFinder.cs" />
     <Compile Include="Routing\UrlProviderCollection.cs" />
     <Compile Include="Routing\UrlProviderCollectionBuilder.cs" />
-    <Compile Include="Search\SearchableApplicationTree.cs" />
-    <Compile Include="Search\SearchableTreeAttribute.cs" />
-    <Compile Include="Search\SearchableTreeCollection.cs" />
-    <Compile Include="Search\SearchableTreeCollectionBuilder.cs" />
     <Compile Include="Search\UmbracoTreeSearcher.cs" />
     <Compile Include="Security\AuthenticationExtensions.cs" />
     <Compile Include="Security\UmbracoSecureDataFormat.cs" />