Extract routes python interface hotfix

[hjabbot]

PolarRoute Pull Request Template

Date: 2024-08-14 Version Number: 0.5.2

Description of change

Moves the extraction of routes into geojson format from cli.py to utils.py in order to make it accessible from a python interface rather that just through the CLI. Feature requested by @davidwilby

Fixes #288

Testing

To ensure that the functionality of the PolarRoute codebase remains consistent throughout the development cycle a testing strategy has been developed, which can be viewed in the document test/testing_strategy.md. This includes a collection of test files which should be run according to which part of the codebase has been altered in a pull request. Please consult the testing strategy to determine which tests need to be run.

• [x] My changes have not altered any of the files listed in the testing strategy Passing reg tests: reg_test.txt

• [ ] My changes result in all required regression tests passing without the need to update test files.

• [ ] My changes require one or more test files to be updated for all regression tests to pass.

Checklist

• [x] My code follows pep8 style guidelines.
• [x] I have commented my code, particularly in hard-to-understand areas.
• [x] I have updated the documentation of the codebase where required.
• [x] My changes generate no new warnings.
• [x] My PR has been made to the 0.5.x branch (DO NOT SUBMIT A PR TO MAIN)