Refactors OptimisationResult class, adds finite cost check for identified parameters

[BradyPlanden]

Description

• Refactors the BaseOptimisers result method,
• Adds finite cost check on optimisation results
• Creates a breaking change for optim.run() as the returned object is now the class object

Issue reference

Fixes #526

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)

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• Code is well-commented, especially in complex or unclear areas.
• 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

Attention: Patch coverage is 97.61905% with 1 line in your changes missing coverage. Please review.

Project coverage is 99.05%. Comparing base (f53d588) to head (42bab27).
Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
pybop/optimisers/base_optimiser.py	96.29%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #527   +/-   ##
========================================
  Coverage    99.05%   99.05%           
========================================
  Files           52       52           
  Lines         3582     3583    +1     
========================================
+ Hits          3548     3549    +1     
  Misses          34       34           

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