Summary:

Adds new parameter use24HourFormat in showTimePicker to display 24 Hour Time Format. Fixes #144919

Before:

showTimePicker(
  context: context,
  initialTime: TimeOfDay(hour: 22, minute: 0),
  builder: (context, child) {
    return MediaQuery(
      data: MediaQuery.of(
        context,
      ).copyWith(alwaysUse24HourFormat: true),
      child: child!,
    );
  },
);

After:

showTimePicker(
  use24HourFormat: true,
  context: context,
  initialTime: TimeOfDay(hour: 22, minute: 0),
 );

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
• I signed the CLA.
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• 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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