Add option to load app props from AWS Parameter Store

[rpoet-jh]

This PR adds the option to load application properties defined in application.yaml from and AWS Parameter Store.

The PR contains the following changes:

• Rename PASS_CORE_BACKEND_USER and PASS_CORE_BACKEND_PASSWORD to PASS_CORE_USER and PASS_CORE_PASSWORD respectively. This will set up usage of these by other services/data loaders in PASS.
• Add spring AWS Parameter Store dep to implement app config environment integration with param store.

The way it works is by using the spring.config.import to specify to load app props from the AWS parameter store. See the AwsParamStoreConfigTest.properties method for an example.

https://docs.awspring.io/spring-cloud-aws/docs/3.0.0/reference/html/index.html#spring-cloud-aws-parameter-store

Note that this PR needs to be approved and merged before the other PR in pass-support. This is because of the pass core user/password env var name change.

[rpoet-jh]

The acceptance tests are failing because pass-docker needs to be updated to use the new pass core user env names. I think this is a case where we will have to merged one of the PRs first to get the other to pass. I'd say to merge this one first, then we can re-run the pass-docker PR to ensure it works.

[markpatton]

Looks good. As mentioned pass-documentation needs to be updated wrt the env variable change.