Models needed for sofc example

[AlexNoring]

Summary/Motivation:

This PR includes new models and changes that are required for the sofc and rsofc flowsheets that will be pushed to examples-pse.

Changes proposed in this PR:

1. Added a new argument to the get_prop() function in natural_gas_PR.py to allow scaled base units
2. Added the CPU unit model and tests
3. Added code to build the sofc rom that calculates sofc voltage and outlet conditions

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.

[codecov[bot]]

Codecov Report

Merging #872 (6d44a4b) into main (0e01fec) will increase coverage by 0.11%. The diff coverage is 93.15%.

@@            Coverage Diff             @@
##             main     #872      +/-   ##
==========================================
+ Coverage   70.20%   70.32%   +0.11%     
==========================================
  Files         574      576       +2     
  Lines       64285    64619     +334     
  Branches    12127    12138      +11     
==========================================
+ Hits        45132    45443     +311     
- Misses      16855    16876      +21     
- Partials     2298     2300       +2     

Impacted Files	Coverage Δ
...xtra/power_generation/properties/natural_gas_PR.py	78.46% <25.00%> (-7.98%)	:arrow_down:
...s/models_extra/power_generation/unit_models/cpu.py	94.71% <94.71%> (ø)
...generation/properties/sofc/sofc_keras_surrogate.py	95.45% <95.45%> (ø)
idaes/ver.py	61.53% <0.00%> (-4.62%)	:arrow_down:
idaes/core/dmf/util.py	55.55% <0.00%> (-0.40%)	:arrow_down:
idaes/core/surrogate/surrogate_block.py	97.46% <0.00%> (+5.06%)	:arrow_up:

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[eslickj]

I'll approve, but you'll have to run black on this thing to get the tests passing.

[ksbeattie]

@AlexNoring any eta on getting to this?

[AlexNoring]

@ksbeattie I'll have some time to work on it by the end of this week.

[ksbeattie]

@AlexNoring, will you be able to get @lbianchi-lbl suggestion above done today? We are due to cut the Aug RC today and would like this PR included, if possible.