Fix CdcAsFlussRow.java file location to match package declaration

The file CdcAsFlussRow.java was incorrectly located in sink/row/row/
directory while its package declaration is org.apache.flink.cdc.connectors.fluss.sink.row.
This mismatch violates Java's requirement that package declaration must
match the file system path.

Moved CdcAsFlussRow.java from sink/row/row/ to sink/row/ to align with:
- Java language specification requirements
- The package declaration
- Other related classes (CdcAsFlussArray.java, CdcAsFlussMap.java)

Author: 春栖