Document, typehint, and rearrange recon classes

[WYVERN2742]

This is part of the software sustainability hackathon, and is part of a larger
project to improve cil's documentation. #1683

Describe your changes

Since the changes are quite large, this PR is limited to the cil.recon folder.

No functional code changes were performed.

• Sorted imports
• Document and typehint functions, following the numpy standard
  • Private functions are not documented.
• Move __init__ to top of class
• Move private functions to bottom of class
• Standardise using " for strings
• Explicitly state classes as abstract classes

Describe any testing you have performed

Please add any demo scripts to CIL-Demos/misc/

Link relevant issues

• Update doc comments, typehinting, and code structure #1683

Checklist when you are ready to request a review

• I have performed a self-review of my code
• I have added docstrings in line with the guidance in the developer guide
• I have implemented unit tests that cover any new or modified functionality
• CHANGELOG.md has been updated with any functionality change
• Request review from all relevant developers
• Change pull request label to 'Waiting for review'

Contribution Notes

Please read and adhere to the developer guide and local patterns and conventions.

• The content of this Pull Request (the Contribution) is intentionally submitted for inclusion in CIL (the Work) under the terms and conditions of the Apache-2.0 License.
• I confirm that the contribution does not violate any intellectual property rights of third parties