Intercept UIScene device log and print a guided warning

[vashworth]

This PR checks for iOS device warnings about UIScene and prints a message from UserMessages. As it stands now, it will not print anything since uisceneMigrationWarning is null. This will be overriden elsewhere.

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
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• 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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[gemini-code-assist]

Code Review

This pull request refactors the iOS device log reading mechanism to introduce a generic LogInterceptor. This new system is then used to intercept and display a guided warning for UIScene related device logs. The refactoring also encapsulates the existing JIT crash log interception into a LogInterceptor. The changes are well-structured and improve the extensibility of log processing. I've found one area for improvement in the new log interception logic.

[gemini-code-assist]

The current implementation of _interceptLog stops processing interceptors after the first match. If the first matching interceptor has excludeFromStream: false, it returns false immediately, and any other interceptors that might also match (and potentially want to exclude the log) are never checked. This could lead to unexpected behavior if multiple interceptors could match the same log line.

To ensure all matching interceptors are processed, you could iterate through all of them, execute their actions, and then decide whether to exclude the log based on whether any of them requested exclusion.

  bool _interceptLog(String message) {
    bool shouldExclude = false;
    for (final LogInterceptor interceptor in _logInterceptors) {
      if (message.contains(interceptor.pattern)) {
        interceptor.action();
        if (interceptor.excludeFromStream) {
          shouldExclude = true;
        }
      }
    }
    return shouldExclude;
  }

[bkonyi]

Nit: an assertion failure?

[auto-submit]

autosubmit label was removed for flutter/flutter/181515, because The base commit of the PR is older than 7 days and can not be merged. Please merge the latest changes from the main into this branch and resubmit the PR.