feat(logging): Structured scope support for Lambda JSON log format in Amazon.Lambda.Logging.AspNetCore

[Lanayx]

Scope properties were silently dropped when AWS_LAMBDA_LOG_FORMAT=JSON. Addresses aws/aws-lambda-dotnet#2122. The final contribution should target aws/aws-lambda-dotnet:master. Closes #2122.

Changes

• LambdaILogger.cs — In the JSON format path, when IncludeScopes=true, iterates the ScopeProvider and for each scope implementing IEnumerable<KeyValuePair<string, object>>, appends {key} placeholders to the message template and the corresponding values to the parameters array. This is necessary because the Lambda JSON formatter (RuntimeSupport) matches template placeholders positionally to args to emit named JSON properties — values without a matching placeholder are ignored. Non-structured scopes (plain strings etc.), null keys, and {OriginalFormat} entries are silently skipped. Non-JSON / scopes-disabled paths are unchanged.

• LoggingTests.cs — Six focused tests covering: single KV scope, nested scopes, scopes disabled, no-scope template preservation, null scope value, and non-structured scope.

• README.md — Documents structured scope behavior in Lambda JSON mode.

Example

// AWS_LAMBDA_LOG_FORMAT=JSON, IncludeScopes=true
using (logger.BeginScope(new Dictionary<string, object> { ["RequestId"] = "abc-123", ["UserId"] = 42 }))
{
    logger.LogInformation("Order {OrderId} placed", orderId);
    // Emits JSON with RequestId, UserId, and OrderId as named properties.
}

Scope properties are appended after message-template properties, so message positional args are unaffected. Nested scopes are collected in provider-enumeration order (outermost first).

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