Create Resharding Instance Metrics Field Name Provider

Create a ReshardingInstanceMetricsFieldNameProvider subclass which implements the abstract functions of ShardingDataTransformInstanceMetricsFieldNameProvider as well as the resharding specific fields below:

• deletesApplied
• insertsApplied
• updatesApplied
• oplogEntriesFetched
• oplogEntriesApplied
• totalApplyTimeElapsedSecs

ReshardingMetricsNew should accept an instance of this class in its constructor and use it when reporting its fields. The existing field name constants should also be removed, where possible.