Fix canonicalization of GpuFileSourceScanExec, GpuShuffleCoalesceExec

[jlowe]

At least part of the issue in #1308 is caused by parts of the query being executed multiple times redundantly because Spark is unable to determine that subsections of the query are identical. This is caused by broken canonicalization where a GPU Exec node is not comparing correctly with a semantically-equivalent copy of itself.

In this case it's the use of a RapidsConf instance as a parameter of the case class. RapidsConf doesn't have an equals method, so two instances will be considered different. However I don't think adding an equals method is the real fix here, as the configs could be slightly different in ways unrelated to the semantics of the node's execution and therefore should still be considered equal with respect to that node's canonicalization.

In the case of GpuShuffleCoalesceExec it was easy, there was only one config value being used, so I replaced the conf parameter with the value from the conf. For GpuFileSourceScanExec it is trickier since there are many config parameters being used, and it already has quite a few arguments. In this case I opted to place the conf instance in a separate parameter list which is excluded from the automatically generated equals and hashcode comparison which is used by Spark plan canonicalization. In our case, there are no RAPIDS config settings that change the semantics for what data is read and how it is presented, so we can safely ignore any RAPIDS configs for purposes of canonicalization.

[jlowe]

build

[jlowe]

This has a bug where an extra argument was added to GpuFileSourceScanExec but otherCopyArgs was not overridden. It can fail queries where the node needs to be copied after it's inserted into the plan. I'll post a followup PR.