Add sorting support to diagnostic APIs

[dakrone]

Description

Some of our APIs can be quite large depending on the number of indices or shards in the cluster. To assist a user (or ourselves) finding what they need from some of these APIs, it would be beneficial if we could sort the output of some of these APIs by certain criteria.

An example of this could look like:

GET /_stats?sort=indices.status:desc,indices.uuid:asc
{
  "_shards": {...},
  "_all": {...},
  "indices": {
    "my-index-001920": {
      "uuid": "b-uuid",
      "status": "open",
      …
    },
    "my-index-002812": {
      "uuid": "d-uuid",
      "status": "open",
      …
    },
    "my-index-000120": {
      "uuid": "a-uuid",
      "status": "closed",
      … 
    }
}

This would also be very helpful for pagination (#87555) and filtering (#88095).

Some APIs that could support sorting:

• Indices stats
• ILM explain
• Get indices (settings/mappings/aliases)
• Index shard stores

[elasticmachine]

Pinging @elastic/es-data-management (Team:Data Management)