Auto-fix/refactoring idea: use safe deference and coalesce instead of contains and ternary operator

e.g. from @brwilkinson

> I have a long list of global variable overrides in every Module ... so much easier to read...


Start by reviewing the issue’s example and screenshot, then inspect how Bicep currently represents or diagnoses `contains` expressions and ternary operators. The issue names no files, tests, or entry points; done would require an agreed refactoring scope plus implementation and tests for the proposed auto-fix.

Written by the indexing model from the issue text.