fix(cloudwatch): fix name of 'MetricAlarmProps' (#1765)

Fixes #1760.

BREAKING CHANGE: Rename 'MetricAarmProps' => 'MetricAlarmProps'.

Author: rix0rrr

packages/@aws-cdk/aws-cloudwatch/lib/alarm.ts

@@ -1,13 +1,13 @@
 import { Construct, Token } from '@aws-cdk/cdk';
 import { CfnAlarm } from './cloudwatch.generated';
 import { HorizontalAnnotation } from './graph';
-import { Dimension, Metric, MetricAarmProps, Statistic, Unit } from './metric';
+import { Dimension, Metric, MetricAlarmProps, Statistic, Unit } from './metric';
 import { parseStatistic } from './util.statistic';
 
 /**
  * Properties for Alarms
  */
-export interface AlarmProps extends MetricAarmProps {
+export interface AlarmProps extends MetricAlarmProps {
   /**
    * The metric to add the alarm on
    *

packages/@aws-cdk/aws-cloudwatch/lib/metric.ts

@@ -148,7 +148,7 @@ export class Metric {
    * Combines both properties that may adjust the metric (aggregation) as well
    * as alarm properties.
    */
-  public newAlarm(scope: cdk.Construct, id: string, props: MetricAarmProps): Alarm {
+  public newAlarm(scope: cdk.Construct, id: string, props: MetricAlarmProps): Alarm {
     return new Alarm(scope, id, {
       metric: this.with({
         statistic: props.statistic,
@@ -296,7 +296,7 @@ export interface MetricCustomization {
 /**
  * Properties needed to make an alarm from a metric
  */
-export interface MetricAarmProps {
+export interface MetricAlarmProps {
   /**
    * The period over which the specified statistic is applied.
    *