sst_dump --command=raw to add index offset information (#10873)

Summary:
Add some extra information in outputs of "sst_dump --command=raw" to help debug some issues. Right now, encoded block handle is printed out. It is more useful to directly print out offset and size.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10873

Test Plan: Manually run it against a file and check the output.

Reviewed By: anand1976

Differential Revision: D40742289

fbshipit-source-id: 04d7de26e7f27e1595a7cc3ac1c1082e4e835b93

table/block_based/block_based_table_reader.cc

@@ -2981,7 +2981,8 @@ Status BlockBasedTable::DumpIndexBlock(std::ostream& out_stream) {
     out_stream << "  HEX    " << user_key.ToString(true) << ": "
                << blockhandles_iter->value().ToString(true,
                                                       rep_->index_has_first_key)
-               << "\n";
+               << " offset " << blockhandles_iter->value().handle.offset()
+               << " size " << blockhandles_iter->value().handle.size() << "\n";
 
     std::string str_key = user_key.ToString();
     std::string res_key("");