fixed CupertinoNavigationBar leading issue

[parkwonhui]

Description

Fixed CupertinoNavigationBar leading issue

Related Issues

#18536

Tests

I added the following tests:
Leading positon of the text in CupertinoNavigationBar should be centered vertically

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This pull request executed golden file tests, but it has not been updated in a while (20+ days). Test results from Gold expire after as many days, so this pull request will need to be updated with a fresh commit in order to get results from Gold.For more guidance, visit Writing a golden file test for package:flutter.

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[Piinks]

(triage) Hi @parkwonhui, this PR has not been updated in a while. Some test are failing and there are merge conflicts. It also looks like the issue is going to resolved by a separate change (#81540), so I am going to close this PR foe now. Thank you for the contribution!