- FreeSql.Repository 增加 filter 参数，现实数据过滤 + 验证；

如：var postRepos = fsql.GetGuidRepository<Post>(a => a.TopicId == 1); postRepos CURD 方法都会以 lambad 条件作为查询或验证，Update/Insert验证错误时会抛出异常。
- ISelect 增加 First/FirstAsync；

FreeSql.Repository/GuidRepository.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Linq.Expressions;
 using System.Text;
 using System.Threading.Tasks;
 
@@ -9,7 +10,7 @@ namespace FreeSql {
 		BaseRepository<TEntity, Guid>
 		where TEntity : class {
 
-		public GuidRepository(IFreeSql fsql) : base(fsql) {
+		public GuidRepository(IFreeSql fsql, Expression<Func<TEntity, bool>> filter) : base(fsql, filter) {
 		}
 
 		public override List<TEntity> Insert(IEnumerable<TEntity> entity) {