feat: add alias for new and existing index

[Bingjiling]

Issue #, if available:

Description of changes:

• Add alias for new and existing index on update/create
• Use alias for update/create
• Tested for
  • Alias is created for existing index upon update/create
  • New index is created with alias
  • Create, update and delete patient using index alias

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[carvantes]

Looks good so far, but I left a comment that needs to be addressed before merging.

Also, we need to make a change to write to aliases instead of indexes at:

fhir-works-on-aws-persistence-ddb/src/ddbToEs/ddbToEsHelper.ts

Line 127 in 0da8a28

index: lowercaseResourceType,

Otherwise the aliases are meaningless.