[#6530] Improved error handling on import_tool task

Signed-off-by: Cory Johns <cjohns@slashdotmedia.com>
[#6530] Add error handling to individual tool importers

Signed-off-by: Tim Van Steenburgh <tvansteenburgh@gmail.com>
[#6530] Refactor error handling into context manager

- Also allows exc to propagate up so task will end in error state

Signed-off-by: Tim Van Steenburgh <tvansteenburgh@gmail.com>