Readimage circ import

[NMiklave]

Describe your changes
Calls to read_image by functions in the visualize and transform subpackages create circular imports, because read_image imports the hyperspectral subpackage. This PR resolves some circular imports by:

• Creating the helper function _read_hyper in readimage, taking over functionality from hyperspectral.read_data.
• Relocating helper functions in hyperspectral.read_data (that are only called by read_data) into the readimage module.
• Redirects hyperspectral.read_data to wrap _read_hyper, to preserve existing workflows.
• Relocating shared helper functions _find_closest and _make_pseudo_rgb from hyperspectral.read_data to the _helpers module.
• Creating a helper for transform.rescale in _helpers.

Type of update
Code cleanup

For the reviewer
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• PR functionality reviewed in a Jupyter Notebook
• All tests pass
• Test coverage remains 100%
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[deepsource-io]

Here's the code health analysis summary for commits 6e23e95..c5af390. View details on DeepSource ↗.

Analysis Summary

Analyzer	Status	Summary	Link
Python	❌ Failure	❗ 11 occurences introduced	View Check ↗
Test coverage	✅ Success		View Check ↗

Code Coverage Report

Metric	Aggregate	Python
Branch Coverage	100%	100%
Composite Coverage	100%	100%
Line Coverage	100%	100%
New Branch Coverage	100%	100%
New Composite Coverage	100%	100%
New Line Coverage	100%, ✅ Above Threshold	100%, ✅ Above Threshold

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