[material_ui] Enable floating_action_button_test

[elliette]

Port over floating_action_button_test from flutter/flutter#184279

Work towards flutter/flutter#182636 and flutter/flutter#188395

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[gemini-code-assist]

Code Review

This pull request removes the @Skip annotations from several test files, refactors imports to use local paths, and extracts the shared findByTooltip helper function into a new finders.dart file. Feedback on the changes suggests using optional chaining instead of a null assertion operator on widget.richMessage in findByTooltip to prevent a potential runtime exception when both message and richMessage are null.

[gemini-code-assist]

Code Review

This pull request removes the @Skip annotation from floating_action_button_test.dart, imports dart:async, reorders the imports, and wraps several Navigator.push calls in unawaited to handle unawaited futures. There are no review comments, and I have no feedback to provide.

[Piinks]

LGTM!