#2275 remove ProcessedSymbolicVariable

[valentinsulzer]

Description

Remove ProcessedSymbolicVariable and has_symbolic_inputs

Fixes #2275

Type of change

Please add a line in the relevant section of CHANGELOG.md to document the change (include PR #) - note reverse order of PR #s. If necessary, also add to the list of breaking changes.

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist:

• No style issues: $ flake8
• All tests pass: $ python run-tests.py --unit
• The documentation builds: $ cd docs and then $ make clean; make html

You can run all three at once, using $ python run-tests.py --quick.

Further checks:

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[codecov]

Codecov Report

Merging #2276 (f550813) into develop (1f01c1e) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##           develop    #2276    +/-   ##
=========================================
  Coverage    99.39%   99.39%            
=========================================
  Files          365      364     -1     
  Lines        20043    19930   -113     
=========================================
- Hits         19921    19810   -111     
+ Misses         122      120     -2     

Impacted Files	Coverage Δ
pybamm/__init__.py	100.00% <ø> (ø)
pybamm/solvers/base_solver.py	100.00% <100.00%> (ø)
pybamm/solvers/casadi_algebraic_solver.py	100.00% <100.00%> (ø)
pybamm/solvers/casadi_solver.py	98.94% <100.00%> (+0.67%)	⬆️
pybamm/solvers/processed_variable.py	100.00% <100.00%> (ø)
pybamm/solvers/solution.py	100.00% <100.00%> (ø)

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[brosaplanella]

Looks good, thanks! If it was in the CHANGELOG already, we should add the link to this PR in the CHANGELOG.