#2368 overload numpy functions

[valentinsulzer]

Description

• Numpy functions can now be called on pybamm symbolic objects. This will return a pybamm symbolic object applying the same function (e.g. np.exp(x) returns pybamm.Exp(x)). Parameter sets in the library have been changed to use numpy functions, but they do not need to be (the old style of calling pybamm functions will still work)
• Binary operators applied to a pybamm object and numpy array return a pybamm binary operator, where previously it raised an error. The numpy array gets converted to a pybamm Vector. This only works with 1D arrays (it could work with other objects, but restricting it to 1D arrays makes things easier for now

Fixes #2368

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: $ pre-commit run (see CONTRIBUTING.md for how to set this up to run automatically when committing locally, in just two lines of code)
• All tests pass: $ python run-tests.py --all
• The documentation builds: $ python run-tests.py --doctest

You can run unit and doctests together 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

Patch coverage: 100.00% and no project coverage change.

Comparison is base (61e04b3) 99.71% compared to head (4facad1) 99.71%.
Report is 6 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #3205   +/-   ##
========================================
  Coverage    99.71%   99.71%           
========================================
  Files          248      248           
  Lines        18808    18830   +22     
========================================
+ Hits         18754    18776   +22     
  Misses          54       54           

Files Changed	Coverage Δ
pybamm/expression_tree/binary_operators.py	100.00% <100.00%> (ø)
pybamm/expression_tree/symbol.py	100.00% <100.00%> (ø)
pybamm/input/parameters/lead_acid/Sulzer2019.py	100.00% <100.00%> (ø)
pybamm/input/parameters/lithium_ion/Ai2020.py	100.00% <100.00%> (ø)
pybamm/input/parameters/lithium_ion/Chen2020.py	100.00% <100.00%> (ø)
...input/parameters/lithium_ion/Chen2020_composite.py	100.00% <100.00%> (ø)
pybamm/input/parameters/lithium_ion/Ecker2015.py	100.00% <100.00%> (ø)
pybamm/input/parameters/lithium_ion/Marquis2019.py	100.00% <100.00%> (ø)
pybamm/input/parameters/lithium_ion/Mohtat2020.py	100.00% <100.00%> (ø)
pybamm/input/parameters/lithium_ion/NCA_Kim2011.py	100.00% <100.00%> (ø)
... and 5 more

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[brosaplanella]

Looks good, thanks! Just a very small comment (you will have to update the CHANGELOG too).