Reduce Copying of RowGroupMetaData and FileMetaData

[tustvold]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

SerializedFileReader and friends currently perform a lot of copying of RowGroupMetadata and FileMetadata, whilst reading indexes and filtering row groups. Neither of these are small or particularly cheap to clone.

Describe the solution you'd like

I would like to reduce the amount of unnecessary work being performed, either by altering the interfaces so data can be moved instead of cloned, or using Arc

Describe alternatives you've considered

Additional context