YT-19324: move YT provider to ydb/library/yql

This commit is formed by the following script: https://paste.yandex-team.ru/6f92e4b8-efc5-4d34-948b-15ee2accd7e7/text.
This commit has zero effect on all projects that depend on YQL.

The summary of changes:
- `yql/providers/yt -> ydb/library/yql/providers/yt `- the whole implementation of YT provider is moved into YDB code base for further export as a part of YT YQL plugin shared library;
- `yql/providers/stat/{expr_nodes,uploader} -> ydb/library/yql/providers/stat/{expr_nodes,uploader}` - a small interface without implementation and the description of stat expr nodes;
- `yql/core/extract_predicate/ut -> ydb/library/yql/core/extract_predicate/ut`;
- `yql/core/{ut,ut_common} -> ydb/library/yql/core/{ut,ut_common}`;
- `yql/core` is gone;
- `yql/library/url_preprocessing -> ydb/library/yql/core/url_preprocessing`.

**NB**: all new targets inside `ydb/` are under `IF (NOT CMAKE_EXPORT)` clause which disables them from open-source cmake generation and ya make build. They will be enabled in the subsequent commits.

1 files changed, 47 insertions, 0 deletions

diff --git a/yt/cpp/mapreduce/interface/io.cpp b/yt/cpp/mapreduce/interface/io.cpp
new file mode 100644
index 00000000000..f97629721a7
--- /dev/null
+++ b/yt/cpp/mapreduce/interface/io.cpp
@@ -0,0 +1,47 @@
+#include "io.h"
+
+#include <yt/cpp/mapreduce/interface/logging/yt_log.h>
+
+#include <util/string/cast.h>
+
+namespace NYT {
+
+////////////////////////////////////////////////////////////////////////////////
+
+TMaybe<size_t> IReaderImplBase::GetReadByteCount() const
+{
+    return Nothing();
+}
+
+i64 IReaderImplBase::GetTabletIndex() const
+{
+    Y_FAIL("Unimplemented");
+}
+
+bool IReaderImplBase::IsEndOfStream() const
+{
+    Y_FAIL("Unimplemented");
+}
+
+bool IReaderImplBase::IsRawReaderExhausted() const
+{
+    Y_FAIL("Unimplemented");
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+namespace NDetail {
+
+void LogTableReaderStatistics(ui64 rowCount, TMaybe<size_t> byteCount)
+{
+    TString byteCountStr = (byteCount ? ::ToString(*byteCount) : "<unknown>");
+    YT_LOG_DEBUG("Table reader has read %v rows, %v bytes",
+        rowCount,
+        byteCountStr);
+}
+
+} // namespace NDetail
+
+////////////////////////////////////////////////////////////////////////////////
+
+} // namespace NYT