Workaround for LSRRO Sweep Circular Import

[MarcusHolly]

Summary/Motivation:

The LSRRO sweep test could not be run due to a circular import:

ImportError: cannot import name '_lsrro_presweep' from partially initialized module 'watertap.flowsheets.lsrro.multi_sweep' (most likely due to a circular import)

Changes proposed in this PR:

• Imports _lsrro_presweep inside of the function rather than at the top of the lsrro flowsheet file

Legal Acknowledgement

By contributing to this software project, I agree to the following terms and conditions for my contribution:

1. I agree my contributions are submitted under the license terms described in the LICENSE.txt file at the top level of this directory.
2. I represent I am authorized to make the contributions and grant the license. If my employer has rights to intellectual property that includes these contributions, I represent that I have received permission to make contributions and grant the required license on behalf of that employer.

[adam-a-a]

This will not fix the issue completely--technically. Maybe I can pitch in since I think I caused this problem with the UCI workshop scramble.

[MarcusHolly]

Will be addressed in #1700