PR: Ensure that LUT reading and writing can occur when path has no known extension.

[KelSolaar]

Summary

This PR ensures that a LUT can be read or written when the given path has no known extension.

References #1212.

Preflight

Code Style and Quality

• Unit tests have been implemented and passed.
• Pyright static checking has been run and passed.
• Pre-commit hooks have been run and passed.
• [N/A] New transformations have been added to the Automatic Colour Conversion Graph.
• [N/A] New transformations have been exported to the relevant namespaces, e.g. colour, colour.models.

Documentation

• [N/A] New features are documented along with examples if relevant.
• [N/A] The documentation is Sphinx and numpydoc compliant.

[coveralls]

coverage: 99.798%. remained the same when pulling d36af26 on feature/lut_write into b2de06a on develop.