[local_auth] support localizedFallbackTitle in IOSAuthMessages

[kaparray]

Description

Add support localizedFallbackTitle in IOSAuthMessages.

Related Issues

flutter/flutter#53205

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[kaparray]

@googlebot I signed it!

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[kaparray]

@a14n please approve or give an answer about PR

[a14n]

Sorry I'm not the right person to review this PR.

[kaparray]

@a14n Sorry 😐 Who review this PR? I need this update in my production app. Thx for help )

[a14n]

You can try to reach to someone on discord in hackers-ecosystem channel.

[kaparray]

What about the review?

[stuartmorgan-g]

We apologize for the long delay in triaging this PR. We’re in the process of overhauling our PR triage system to respond much more quickly, as well as working through the backlog.

With the addition of #2489 it seems like this should only be supported in the non-biometric path, so this PR would need to be updated.

I also suspect that in that path we want the default to be nil rather than @""; deciding how the default behavior should be handled (whether to disable, or use nil) needs discussion, and due to the subtleties there this PR would definitely need a test.

[stuartmorgan-g]

Thank you for your contribution. I'm going to close this PR for now since there are outstanding comments, just to get this off our PR review queue. Please don't hesitate to submit a new PR if you have the time to address the review comments. Thanks!