Replace `set_lhs_units_from_lhs` with `evaluate_units_and_fix`

[MichaelClerx]

Description

See #273

Types of changes

• [x] New feature (non-breaking change which adds functionality)

Checklist:

• [x] I have updated all documentation necessary.
• [x] I have checked spelling in (new) comments.

Testing

• [X] Testing is done automatically and codecov shows test coverage

[codecov[bot]]

Codecov Report

Merging #275 into develop will decrease coverage by 0.00%. The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop     #275      +/-   ##
===========================================
- Coverage    97.45%   97.44%   -0.01%     
===========================================
  Files            7        7              
  Lines         1334     1329       -5     
  Branches       287      286       -1     
===========================================
- Hits          1300     1295       -5     
  Misses          15       15              
  Partials        19       19              

Impacted Files	Coverage Δ
cellmlmanip/units.py	98.37% <100.00%> (-0.03%)	:arrow_down:

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