[parser] model: support add extra partition ID column (#1010)
[parser] model: support add extra partition ID column (#1010)

define ExtraPidColID
add NewExtraPartitionIDColInfo to support create extra pid column
c4pt0r/tidb,kyle-wang/tidb,ngaut/tidb,kyle-wang/tidb,c4pt0r/tidb,pingcap/tidb,ngaut/tidb,kyle-wang/tidb,pingcap/tidb,pingcap/tidb,pingcap/tidb,c4pt0r/tidb,ngaut/tidb,coocood/tidb,coocood/tidb,pingcap/tidb,pingcap/tidb,c4pt0r/tidb,ngaut/tidb,c4pt0r/tidb,ngaut/tidb,kyle-wang/tidb,kyle-wang/tidb,c4pt0r/tidb,ngaut/tidb,kyle-wang/tidb