Cherry-pick #22228 to 7.x: [Filebeat] Rename awscloudwatch input to aws-cloudwatch input

[kaiyan-sheng]

Cherry-pick of PR #22228 to 7.x branch. Original message:

What does this PR do?

This PR is to rename awscloudwatch input to aws-cloudwatch to follow the naming convention for Filebeat inputs.
After this PR get cherry-picked into 7.x, we can remove support of awscloudwatch. Or create a separate issue to remove old names in 8.0.

Deprecation warning log message is also added to this PR:

2020-10-28T12:41:21.556-0600    WARN    [aws-cloudwatch]        awscloudwatch/input.go:93       awscloudwatch input name is deprecated, please use aws-cloudwatch instead

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

How to test this PR locally

Make sure both awscloudwatch and aws-cloudwatch input work:

filebeat.inputs:
  - type: awscloudwatch
    credential_profile_name: elastic-beats
    log_group_arn: arn:aws:logs:us-east-1:428152502467:log-group:test:*
    region: us-east-1
    scan_frequency: 30s
    start_position: beginning
    api_timeout: 5m

and

filebeat.inputs:
  - type: aws-cloudwatch
    credential_profile_name: elastic-beats
    log_group_arn: arn:aws:logs:us-east-1:428152502467:log-group:test:*
    region: us-east-1
    scan_frequency: 30s
    start_position: beginning
    api_timeout: 5m

Related issues

• Relates [Filebeat] Rename googlecloud module to gcp module #22214

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Passed	4472
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Total	5039

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• Build Cause: [Pull request #22524 opened]

• Start Time: 2020-11-10T17:27:15.702+0000

• Duration: 48 min 25 sec

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Test	Results
Failed	0
Passed	4472
Skipped	567
Total	5039