Helmholtz EoS external functions not available in NGCC Example

[AlexNoring]

The NGCC example flowsheet is displaying an error on the webpage.

NGCC Baseline and Turndown

2024-05-28 17:17:05 [ERROR] idaes.core.base.process_block: Failure in build: fs.gt.prop_water
Traceback (most recent call last):
  File "/home/docs/checkouts/readthedocs.org/user_builds/idaes-examples/envs/latest/lib/python3.8/site-packages/idaes/core/base/process_block.py", line 41, in _rule_default
    b.build()
  File "/home/docs/checkouts/readthedocs.org/user_builds/idaes-examples/envs/latest/lib/python3.8/site-packages/idaes/models/properties/general_helmholtz/helmholtz_functions.py", line 1441, in build
    raise RuntimeError("Helmholtz EoS external functions not available")
RuntimeError: Helmholtz EoS external functions not available

[andrewlee94]

This may be related to #115