Rename have_x to has_x to improve how logic reads

[kratman]

Description

Minor change to the function names so the logic reads:

if pybamm has something

instead of

if pybamm have something

Key checklist:

• No style issues: $ pre-commit run (or $ nox -s pre-commit) (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 (or $ nox -s tests)
• The documentation builds: $ python run-tests.py --doctest (or $ nox -s doctests)

You can run integration tests, unit tests, and doctests together at once, using $ python run-tests.py --quick (or $ nox -s quick).

Further checks:

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

[kratman]

Still need to do the changelog

[agriyakhetarpal]

Thanks for splitting it into a different PR, @kratman, looks good to me!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.42%. Comparing base (5fdee8a) to head (c2fe6cd).
Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #4398   +/-   ##
========================================
  Coverage    99.42%   99.42%           
========================================
  Files          292      292           
  Lines        22215    22215           
========================================
  Hits         22087    22087           
  Misses         128      128           

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