Add auto_roi method

[HaleySchuhl]

Describe your changes
A clear and concise description of what changes are made by this pull request.
What was the previous functionality (if relevant) and what can we do now with
these changes.

Type of update
Is this a:

• New feature or feature enhancement
• Work in progress

Associated issues
#1509

Additional context
Add any other context about the problem here.

For the reviewer
See this page for instructions on how to review the pull request.

• PR functionality reviewed in a Jupyter Notebook
• All tests pass
• Test coverage remains 100%
• Documentation tested
• New documentation pages added to plantcv/mkdocs.yml
• Changes to function input/output signatures added to updating.md
• Code reviewed
• PR approved

[deepsource-io]

Here's the code health analysis summary for commits 1429294..8f29edf. View details on DeepSource ↗.

Analysis Summary

Analyzer	Status	Summary	Link
Python	❌ Failure	❗ 44 occurences introduced	View Check ↗
Test coverage	❌ Failure	❗ 1 occurence introduced 🚨 1 failing metric	View Check ↗

Code Coverage Report

Metric	Aggregate	Python
Branch Coverage	100%	100%
Composite Coverage	99.6% (down 0.4% from main)	99.6% (down 0.4% from main)
Line Coverage	99.6% (down 0.4% from main)	99.6% (down 0.4% from main)
New Branch Coverage	100%	100%
New Composite Coverage	4.4%	4.4%
New Line Coverage	4.4%, ❌ Below Threshold	4.4%, ❌ Below Threshold

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