##### 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.
version_added: 2.8
  purge_tags:
    description: Whether the I(tags) argument should cause tags not in the list to
      be removed
    version_added: 2.8
    default: False
    type: bool
  purge_grants:
    description: Whether the I(grants) argument should cause grants not in the list to
      be removed
    default: False
    version_added: 2.8
    type: bool
  grants:
    description:
      - A list of grants to apply to the key. Each item must contain I(grantee_principal).
        Each item can optionally contain I(retiring_principal), I(operations), I(constraints),
        I(name).
      - Valid operations are C(Decrypt), C(Encrypt), C(GenerateDataKey), C(GenerateDataKeyWithoutPlaintext),
        C(ReEncryptFrom), C(ReEncryptTo), C(CreateGrant), C(RetireGrant), C(DescribeKey), C(Verify) and
        C(Sign)
      - Constraints is a dict containing C(encryption_context_subset) or C(encryption_context_equals),
        either or both being a dict specifying an encryption context match.
        See U(https://docs.aws.amazon.com/kms/latest/APIReference/API_GrantConstraints.html)
      - I(grantee_principal) and I(retiring_principal) must be ARNs
    version_added: 2.8
  policy:
    description:
      - policy to apply to the KMS key
      - See U(https://docs.aws.amazon.com/kms/latest/developerguide/key-policies.html)