parser: allow user-defined rows_event decode func

[GMHDBJD]

add RowsEventDecodeFunc in BinlogSyncerConfig that allow user-defined rows_event decode func

[lance6716]

Also we have planed some use cases of this feature, such as skipping decoding rows events of uninterested table. But in order to do that, we need to know the table name of this RowsEvent. In the original Decode function, the table name is written to RowsEvent.Table by accessing private members

	e.TableID = FixedLengthInt(data[0:e.tableIDSize])
...
	e.Table, ok = e.tables[e.TableID]

and our customized RowsEventDecodeFunc can not do that.

Maybe we should adjust more code? Or we inject the decoding function at e.decodeRows?

[lance6716]

maybe we can set the default value to (*RowsEvent).Decode, so in parseEvent we don't need to check it many times.

[GMHDBJD]

and our customized RowsEventDecodeFunc can not do that.

rowsEventDecodeFunc = func(re *replication.RowsEvent, data []byte) error {
			_, err := re.DecodeHeader(data)
			tb := &filter.Table{
				Schema: string(re.Table.Schema),
				Name:   string(re.Table.Table),
			}
}