This ticket is to convert all commands on the chunk migrations path into IDL rather than using custom parsing and to introduce timestamps wherever they are missing.

The chunk migrations path is:

1. moveChunk on MongoS
2. _configsvrMoveChunk on the CSRS
3. _shardsvrMoveChunk on the donor shard
4. _configsvrCommitChunkMigration on the CSRS

Commands which are on the Router only should be put under cluster_commands.idl so they only link on MongoS

Commands which are exchanged between Router and CSRS or Shards should be under sharded_ddl_commands.idl so they are linked both on MongoS and MongoD

Commands which are exchanged between Shards/CSRS only should be in an IDL under https://github.com/mongodb/mongo/tree/master/src/mongo/db/s so that they link on MongoD only.