[unified_analytics] ☂️ Top-Level tool analytics consent notification

[pq]

Issue to track work to update tools to flow first-run state down to sub-tools via ENV variables.

This includes work in package:unified_analytics

• [unified analytics] add utilities to compute analytics ENV vars #2343

and updates to ecosystem clients/tools:

• [analytics] Update the Dart Plugin to set analytics ENV variables when invoking sub-tools flutter/dart-intellij-third-party#281
• [analytics] Update the Flutter Plugin to set analytics ENV variables when invoking sub-tools flutter/flutter-intellij#8850
• [analytics] Update Dart Code to set analytics ENV variables when invoking sub-tools
• [analytics] Update the Dart CLI to set analytics ENV variables when invoking sub-tools sdk#62876
• [analytics] Update the Flutter CLI to set analytics ENV variables when invoking sub-tools
• [analytics] Update devtools to set analytics ENV variables when invoking sub-tools flutter/devtools#9702
• [analytics] Update DAS to read (and pass) analytics ENV variables sdk#62875