##### SUMMARY
If you pass aws_kms an existing key_id and no alias, it throws exceptions

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
lib/ansible/modules/cloud/amazon/aws_kms.py

##### ANSIBLE VERSION
```
ansible 2.8.2
  config file = /home/mchappel/.ansible.cfg
  configured module search path = [u'/home/mchappel/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python2.7/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 2.7.5 (default, Jun 11 2019, 12:19:05) [GCC 4.8.5 20150623 (Red Hat 4.8.5-36)]
```

##### CONFIGURATION
```
DEFAULT_CALLBACK_WHITELIST(/home/mchappel/.ansible.cfg) = [u'timer', u'profile_tasks']
DEFAULT_VAULT_IDENTITY_LIST(/home/mchappel/.ansible.cfg) = [u'original@/home/mchappel/.ansible/secrets/original', u'ssl@/home/mchappel/.ansible/secrets/ssl', u'jenkins@/home/mchappel/.ansible/secrets/jenkins']
HOST_KEY_CHECKING(/home/mchappel/.ansible.cfg) = False
RETRY_FILES_ENABLED(/home/mchappel/.ansible.cfg) = False
```

##### OS / ENVIRONMENT
RHEL7

##### STEPS TO REPRODUCE
```
     - name: Update Policy on key to match AWS Console generate policy
       aws_kms:
        key_id: '{{ new_key["keys"][0]["key_id"] }}'
         policy: "{{ lookup('template', 'console-policy.j2') | to_json }}"
       register: kms_policy_changed
```

##### EXPECTED RESULTS
Key successfully updated


##### ACTUAL RESULTS
Exception.  (There's actually a couple of places that need updating)


##### ADDITIONAL DETAILS
@willthames 

https://github.com/tremble/ansible/tree/aws_kms_keyid_only contains updated tests and a fix.  I'll submit a PR once we know what order everything's likely to get merged in.  Side effect of the change, aws_kms is substantially faster, as a result I had to more the iam_role creation in the test suite.
if to_remove:
        for grant in to_remove:
            try:
                connection.retire_grant(KeyId=key['key_arn'], GrantId=grant['grant_id'])
                changed = True
            except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
                module.fail_json_aws(e, msg="Unable to retire grant")
    if to_add:
        for grant in to_add:
            grant_params = convert_grant_params(grant, key)
            try:
                connection.create_grant(**grant_params)
                changed = True
            except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
                module.fail_json_aws(e, msg="Unable to create grant")
    
    result = get_key_details(connection, module, key['key_id'])
    module.exit_json(changed=changed, **result)
def create_key(connection, module):
    params = dict(BypassPolicyLockoutSafetyCheck=False,
                  Tags=ansible_dict_to_boto3_tag_list(module.params['tags'], tag_name_key_name='TagKey', tag_value_key_name='TagValue'),
                  KeyUsage='ENCRYPT_DECRYPT',
                  Origin='AWS_KMS')
    if module.params.get('description'):
        params['Description'] = module.params['description']
    if module.params.get('policy'):
        params['Policy'] = module.params['policy']
    try:
        result = connection.create_key(**params)['KeyMetadata']
    except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e: