Move `Inter_Backend_File_Operations_Spec` from `AWS_Tests` to new suite `Library_Integration_Tests`

[radeusgd]

The file Inter_Backend_File_Operations_Spec was put in AWS_Tests because it needs to access S3_File and I didn't want to create new suites for it back when adding suites was a pain. Now it is easier (because the test directory is automatically scanned in discover_standard_library_tests), so maybe it's better to add a separate suite - so that once there are more backends it will be the more appropriate place to test their interactions.

We just need to keep in mind to ensure this is still run in the Extra Nightly Tests workflow, so we need to accordingly update the Tests::StdCloudRelated test selection.