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 63.15789% with 42 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.67%. Comparing base (4628a65) to head (def7b33).
⚠️ Report is 50 commits behind head on develop.

Files with missing lines	Patch %	Lines
pybop/optimisers/ep_bolfi_optimiser.py	27.77%	26 Missing ⚠️
pybop/costs/feature_distances.py	61.11%	7 Missing ⚠️
pybop/samplers/base_sampler.py	70.58%	5 Missing ⚠️
pybop/plot/predictive.py	90.00%	3 Missing ⚠️
pybop/costs/base_cost.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #918      +/-   ##
===========================================
+ Coverage    89.41%   90.67%   +1.25%     
===========================================
  Files           63       74      +11     
  Lines         4857     5760     +903     
===========================================
+ Hits          4343     5223     +880     
- Misses         514      537      +23     

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