feat(notifications): added notifications for usage thresholds, overages, and welcome emails

[waleedlatif1]

Summary

Brief description of what this PR does and why.

Fixes #(issue)

Type of Change

• [ ] Bug fix
• [ ] New feature
• [ ] Breaking change
• [ ] Documentation
• [ ] Other: ___________

Testing

How has this been tested? What should reviewers focus on?

Checklist

• [ ] Code follows project style guidelines
• [ ] Self-reviewed my changes
• [ ] Tests added/updated and passing
• [ ] No new warnings introduced
• [ ] I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

Screenshots/Videos

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Project	Deployment	Preview	Comments	Updated (UTC)
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