Add "treat_missing_data" as variable for the cloudwatch alarm

## Describe the Feature

When I create EC2 instances, I also attach specific run schedules to them. This causes alerting when the CloudWatch checks see missing data while they are offline.

I would like add the treat_missing_data variable to the module, so i can set the CloudWatch alarm to ignore missing data.

## Expected Behavior

I specifying treat_missing_data would create a cloudwatch alarm that honors the variable value
[treat_missing_data](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/cloudwatch_metric_alarm#treat_missing_data)

## Use Case

This is valuable to me because we use this tool called "Marbot", which alerts automatically for any cloudwatch alarms. Insufficient data falling into this scope. I'd like my EC2 alarms to stay in a "Good" state, when we shut them down for the weekend.

## Describe Ideal Solution

Simple version updating allowing me to use treat_missing_data as a variable

## Alternatives Considered

I've looked into somehow editing the alarm after this module creates it, although im not sure this is best practice or feasible

## Additional Context