feat(logging): Add support for custom log stream name formatters

[cadivus]

• PR title and description conform to Pull Request guidelines.

Issue #, if available:

Description of changes:
This add the option to set a custom formatter for Cloudwatch logstrem names.

How did you test these changes?
Using a sample app. The formatter is set like this:

// Create custom log stream name formatter
val customFormatter = LogStreamNameFormatter { context ->
    val dateFormat = SimpleDateFormat("yyyy-MM-dd", Locale.US)
    val date = dateFormat.format(Date())
    val userId = context.userId ?: "anonymous"
    "cloudwatch-cognito-$date-${context.deviceId}-$userId"
}

// Add CloudWatch Logging plugin with custom formatter
Amplify.addPlugin(AWSCloudWatchLoggingPlugin(logStreamNameFormatter = customFormatter))

Documentation update required?

• No
• Yes (Please include a PR link for the documentation update)

General Checklist

• Added Unit Tests
• Added Integration Tests
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)
• Ensure commit message has the appropriate scope (e.g fix(storage): message, feat(auth): message, chore(all): message)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

❌ Patch coverage is 41.17647% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.78%. Comparing base (232cc21) to head (8c225f2).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3181      +/-   ##
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- Coverage   54.80%   54.78%   -0.03%     
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  Files        1048     1049       +1     
  Lines       31344    31356      +12     
  Branches     4694     4695       +1     
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  Hits        17178    17178              
- Misses      12358    12370      +12     
  Partials     1808     1808              

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