Add new OS utils for DRY file handling

[mxkpp]

Expands OS utils for further DRYifying operations of file handle closing and file removal.

Applies the new OS utils throughout to regrid.py.

Additions

• Various functions added to os_utils.py

Removals

Changes

• Added option to ignore FileNotFoundError during attempts to remove a file
• Replaced many copies of repeated file handling blocks in regrid.py with higher-level equivalent calls to the new functions.
• Details of log messages around file handling are now determined dynamically from the file handle provided.

Testing

1. Ran calibrations and forecasts in RTE and watched log messages after building with ENV FORCING_LOGLEVEL=DEBUG

Screenshots

Notes

Todos

Checklist

• PR has an informative and human-readable title
• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows project standards (link if applicable)
• Passes all existing automated tests
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future todos are captured in comments
• Visually tested in supported browsers and devices (see checklist below 👇)
• Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)
• Reviewers requested with the Reviewers tool ➡️

Testing checklist

Target Environment support

• Linux

[mdeshotel]

Looks good to me.