Add barrierBuilder support to Material dialogs - #190393

This adds barrierBuilder to showDialog, showAdaptiveDialog, and DialogRoute, continuing PR #187992.

Closes #21039

Pre-launch Checklist

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• I listed at least one issue that this PR fixes in the description above.
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• I added new tests to check the change I am making, or this PR is test-exempt.
• I followed the breaking change policy and added Data Driven Fixes where supported.
• All existing and new tests are passing.

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