Add plot of predictions

[NicolaCourtier]

Description

Adding the predictive plot from @YannickNoelStephanKuhn's PR #854.

Type of change

Please add a line in the relevant section of CHANGELOG.md to document the change (include PR #).

Important checks:

Please confirm the following before marking the PR as ready for review:

• 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: nox -s tests
• The documentation builds: nox -s doctest
• Code is commented for hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[codecov]

Codecov Report

❌ Patch coverage is 85.98131% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.06%. Comparing base (4628a65) to head (4641acc).
⚠️ Report is 54 commits behind head on develop.

Files with missing lines	Patch %	Lines
pybop/optimisers/ep_bolfi_optimiser.py	80.64%	6 Missing ⚠️
pybop/samplers/base_sampler.py	70.58%	5 Missing ⚠️
pybop/plot/predictive.py	90.62%	3 Missing ⚠️
pybop/costs/feature_distances.py	92.30%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #918      +/-   ##
===========================================
+ Coverage    89.41%   92.06%   +2.65%     
===========================================
  Files           63       74      +11     
  Lines         4857     5762     +905     
===========================================
+ Hits          4343     5305     +962     
+ Misses         514      457      -57     

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[SarahRo]

Looks good. Thank you. Would it make sense to look at the test coverage before merging?