Couple fixes for clangd language server

- yt/client: include async_stream.h in file_reader.h
  NApi::IFileReader needs NConcurrency::IAsyncZeroCopyInputStream.

- Declare yt/yt/client/api/rpc_proxy/protocol_version_variables.h using CONFIGURE_FILE
  Otherwise resulting file does not materialize after:
  ya make --build-all --force-build-depends --replace-result --add-result=.h yt/yt/client/

  Proper source file generation is required at least for making clangd happy.

---

Pull Request resolved: ytsaurus/ytsaurus#894
commit_hash:b27f7963bc113543c0ac3842f78636be4f33416f

yt/yt/client/api/file_reader.h

@@ -6,6 +6,7 @@
 #include <yt/yt/client/object_client/public.h>
 
 #include <yt/yt/core/concurrency/public.h>
+#include <yt/yt/core/concurrency/async_stream.h>
 
 namespace NYT::NApi {
 

yt/yt/client/ya.make

@@ -198,6 +198,11 @@ SRCS(
     kafka/requests.cpp
 )
 
+CONFIGURE_FILE(
+    api/rpc_proxy/protocol_version_variables.h.in
+    api/rpc_proxy/protocol_version_variables.h
+)
+
 SRCS(
     ${YT_SRCS}
     yt/yt/client/api/rpc_proxy/protocol_version_variables.h.in