[`unconventional-import-alias`] Fix infinite loop between ICN001 and I002 (`ICN001`) (#15480)
## Summary
This fixes the infinite loop reported in #14389 by raising an error to
the user about conflicting ICN001 (`unconventional-import-alias`) and
I002 (`missing-required-import`) configuration options.
## Test Plan
Added a CLI integration test reproducing the old behavior and then
confirming the fix.
Closes #14389
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Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>