Adds FittingProblem arg for model rebuild on evaluation, DFN examples and data-generation scripts

[BradyPlanden]

Description

Completes the following:

• Adds an optional arg to FittingProblem for building on evaluation or not. The default is False which is a breaking change, but I believe it represents the fact that most parameters won't need rebuilding. This combines the build interface into a single class, and avoids sharp-edges using model.build standalone.
• Creates initial synthetic data generation examples
  • Aligns our examples to better represent true PyBOP usage
  • Allows us to filter the model.predict output for discontinuities that occur from multi-step experiments (this currently causes large issues with the interpolated IDAKLU)
• Adds DFN identification examples

Issue reference

Fixes #662

Review

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• Updated the CHANGELOG.md in reverse chronological order (newest at the top) with a concise description of the changes, including the PR number.
• Noted any breaking changes, including details on how it might impact existing functionality.

Type of change

• New Feature: A non-breaking change that adds new functionality.
• Optimization: A code change that improves performance.
• Examples: A change to existing or additional examples.
• Bug Fix: A non-breaking change that addresses an issue.
• Documentation: Updates to documentation or new documentation for new features.
• Refactoring: Non-functional changes that improve the codebase.
• Style: Non-functional changes related to code style (formatting, naming, etc).
• Testing: Additional tests to improve coverage or confirm functionality.
• Other: (Insert description of change)

Key checklist:

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• All unit tests pass: $ nox -s tests
• The documentation builds: $ nox -s doctest

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• Added tests that prove my fix is effective or that my feature works.
• Checked that coverage remains or improves, and added tests if necessary to maintain or increase coverage.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.23%. Comparing base (828a8e3) to head (5281260).
Report is 3 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #663      +/-   ##
===========================================
- Coverage    99.27%   99.23%   -0.05%     
===========================================
  Files           64       66       +2     
  Lines         4813     4817       +4     
===========================================
+ Hits          4778     4780       +2     
- Misses          35       37       +2     

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