Create a new ShardingDDLCoordinator for the dropIndexes command called 'DropIndexesCoordinator'.

This version of the coordinator will behave similarly to how dropIndexes currently works, meaning that we will not yet ensure that all operations succeed or fail atomically. 

The goals of this task are:

• Create a new coordinator for dropIndexes and instantiate it from shardsvr_drop_indexes.cpp when the feature flag `featureFlagDropIndexesDDLCoordinator` is enabled.
• Add a single phase to the coordinator called 'DropIndexes'
• Under that phase, call `_shardsvrDropIndexesParticipant` against all the shards owning chunks. To do that, we'll use the CollectionRouter utility.
• Retry the failed `_shardsvrDropIndexesParticipant` requests only if it returns a retryable failure.