Add AWS Cost Explorer forecast functionality to CloudFormation template

[NithinChandranR-AWS]

Description of changes:

**This PR attempts to add AWS Cost Explorer forecast functionality to the CUDOS framework. **

This implementation:

1. Creates a Lambda function that generates cost forecasts using the Cost Explorer API
2. Stores forecast data in S3 in a format compatible with QuickSight
3. Generates a QuickSight manifest file for easy data import
4. Updates daily on a schedule
5. Provides outputs with S3 paths for the data and manifest

New Parameters:

• DeployForecastDashboard : Enable/disable forecast functionality (default: no)
• ForecastPeriod : Number of days to forecast (default: 90)
• ForecastGranularity: DAILY or MONTHLY granularity (default: DAILY)
• ForecastMetrics: Metrics to forecast (default: UNBLENDED_COST,BLENDED_COST)
• ForecastDimensions: Dimensions to forecast by (default: SERVICE,LINKED_ACCOUNT,REGION)
• ForecastScheduleExpression: Schedule for forecast data refresh (default: daily at 1 AM UTC)

Manual QuickSight Integration:
After deploying the template with forecast functionality enabled:

1. Navigate to QuickSight → Datasets → New dataset
2. Select S3 as the data source
3. Use the manifest URL from the CloudFormation outputs (ForecastManifestPath)
4. Create visualizations based on the forecast data

Documentation:

• Added documentation in docs/cost-forecast.md

Testing:

• Tested in both development and production environments
• Verified forecast data generation
• Verified QuickSight data import"
  --repo aws-samples/aws-cudos-framework-deployment
  --base main

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