[nakultt]

Issue #, if available: #555

Description of changes:

Adds events.CloudWatchAlarmEvent, the payload CloudWatch sends when a Lambda function is configured directly as an alarm action (docs). The existing CloudWatchAlarmSNSPayload only covers the SNS-delivered format.

• Metric alarms: configuration.metrics with metricStat (namespace, name, dimensions, period, stat, unit) and returnData
• Composite alarms: alarmRule, actionsSuppressor, wait/extension periods, and actionsSuppressedBy/actionsSuppressedReason on the state
• Alarm tags: alarmTags and alarmTagsStatus

Notes:

• Timestamps are kept as string because CloudWatch uses a +0000 offset (e.g. 2023-08-04T12:36:15.490+0000) that time.Time can't unmarshal. This matches CloudWatchAlarmSNSPayload.StateChangeTime.
• reasonData stays a JSON-encoded string, as delivered by CloudWatch.
• Types use a CloudWatchAlarm prefix to avoid clashing with the SNS payload types (CloudWatchMetric, CloudWatchMetricStat, ...), which use PascalCase JSON keys.
• Log-alarm configuration fields aren't modelled yet; those events still unmarshal (extra fields are ignored). Happy to add them here or in a follow-up.

Testing: the fixtures are the documented metric and composite alarm example events. The tests round-trip both through json.Unmarshal/json.Marshal and check key fields, plus the malformed-JSON check.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.04%. Comparing base (4111853) to head (d9e337c).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #653   +/-   ##
=======================================
  Coverage   82.04%   82.04%           
=======================================
  Files          37       37           
  Lines        1487     1487           
=======================================
  Hits         1220     1220           
  Misses        264      264           
  Partials        3        3           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.