Added Details to result and fixed typo in Run

[Darya-Tolmeneva]

This update extends the gRPC executor to include Details from gRPC status responses, returning them as JSON-serializable objects for better error visibility.
Additionally, a typo was fixed where Systemout was mistakenly used instead of Systemerr during stderr JSON parsing.

[Copilot]

Pull Request Overview

This PR enhances the gRPC executor by adding support for capturing and returning gRPC status details, and corrects a critical bug where stderr output was incorrectly parsed into the stdout JSON field.

• Added Details field to the Result struct to capture gRPC error details as JSON-serializable objects
• Implemented logic in OnReceiveTrailers to extract and marshal gRPC status details
• Fixed incorrect field assignment where Systemout was used instead of Systemerr when parsing stderr JSON

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[Copilot]

The marshal-then-unmarshal pattern is inefficient. Consider using type assertion or reflection to convert the detail directly to map[string]interface{}, or store the original detail objects if they're already serializable.

Suggested change

	jsonBytes, err := json.Marshal(d)
	if err != nil {
	continue
	}
	var detailMap map[string]interface{}
	if err := json.Unmarshal(jsonBytes, &detailMap); err != nil {
	continue
	var detailMap map[string]interface{}
	// If d is already a map[string]interface{}, use it directly
	if m, ok := d.(map[string]interface{}); ok {
	detailMap = m
	} else {
	// Use mapstructure to decode struct fields into map
	err := mapstructure.Decode(d, &detailMap)
	if err != nil {
	continue
	}

[Copilot]

Silent error handling with 'continue' makes debugging difficult. Consider logging errors when detail marshaling fails so issues with specific detail types can be identified and addressed.