Fix Issue 21272 - Overzealous and inconsistent foreach shadowing deprecations for nested functions

[RazvanN7]

If we have declarations inside the scope of a foreach statement, we need to extract the function that contains the foreach and check for shadowing only the scope of that function.

[dlang-bot]

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	21272	regression	Overzealous and inconsistent foreach shadowing deprecations for nested functions

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "stable + dmd#11790"

[RazvanN7]

DAutoTest failure seems unrelated.

[CyberShadow]

Thanks!