Bug Fix: Improper use of `cls`

[RHammond2]

This PR fixes an issue where Simulation.from_config() generates the cls object while referencing cls properties improperly, instead of config.

[codecov[bot]]

Codecov Report

Patch and project coverage have no change.

Comparison is base (4cfe1ee) 54.69% compared to head (85e4ea5) 54.69%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #110 +/- ## ======================================== Coverage 54.69% 54.69% ======================================== Files 21 21 Lines 3607 3607 Branches 730 730 ======================================== Hits 1973 1973 Misses 1512 1512 Partials 122 122 ``` | [Files Changed](https://app.codecov.io/gh/WISDEM/WOMBAT/pull/110?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=WISDEM) | Coverage Δ | | |---|---|---| | [wombat/core/simulation\_api.py](https://app.codecov.io/gh/WISDEM/WOMBAT/pull/110?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=WISDEM#diff-d29tYmF0L2NvcmUvc2ltdWxhdGlvbl9hcGkucHk=) | `51.69% <ø> (ø)` | |

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