[FEATURE] Add alias option to Shrink action to allow aliasing original index name to newly created index after deletion of original index

The Shrink action provides a great way to process a batch of indices, shrink them to new indices and delete the originals.

It would be super handy to also have the option to add the alias for the original index name to the newly created shrunken index for each index processed.

Currently you have to either:

- Leave a bunch of duplicate indices around until the end of the batch then delete+alias, putting unnecessary pressure on resources depending on the size of the indices/batch...or
- run with missing indices until the end of the batch then add the aliases at the end of the batch

And with the alias+delete steps, these are also not atomic and it would be neater if Curator's Alias action also had the option to use the `remove_index` action provided by the Index Alias API:
https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-aliases.html#CO146-3

The issue does not name files or tests. Start by locating the Shrink and Alias action implementations and their Elasticsearch index-alias handling, then review the linked Index Alias API documentation. Done means the Shrink action can optionally alias each original name to its new index after deletion, with the intended alias and removal behavior covered by tests.

Written by the indexing model from the issue text.