[Console] Support index template comments

[a03nikki]

Describe the feature:

In Dev Tool's Console, it would be helpful if it did not mark comments in templates as errors and would align the JSON as well.

Describe a specific use case for the feature:

It causes confusion as the comment lines are marked as errors. Plus, the "Auto indent" stops working when comments are present.

For example, let's take this example without the leading white space

PUT _template/test_1
{
"index_patterns": ["test-*"],
"mappings": {
"properties": {
"http": {
"properties": {
"session": {
"properties": {
"id": {
"type": "keyword"
}
}
}
}
}
}
}
}

✅ Without the comment, if you run "Auto indent" on it, the leading white space is added back in

PUT _template/test_1
{
  "index_patterns": [
    "test-*"
  ],
  "mappings": {
    "properties": {
      "http": {
        "properties": {
          "session": {
            "properties": {
              "id": {
                "type": "keyword"
              }
            }
          }
        }
      }
    }
  }
}

However, if a comment is thrown into the mix

PUT _template/test_1
{
"index_patterns": ["test-*"],
"mappings": {
"properties": {
"http": {
"properties": {
"session": {
/* custom field */
"properties": {
"id": {
"type": "keyword"
}
}
}
}
}
}
}
}

🔴 It does not format.

To save your eyes, here is same text manually aligned but with the comment

PUT _template/test_1
{
  "index_patterns": [
    "test-*"
  ], 
  "mappings": {
    "properties": {
      "http": {
        "properties": {
          "session": {
            /* custom field */
            "properties": {
              "id": {
                "type": "keyword"
              }
            }
          }
        }
      }
    }
  }
}

🔴 But in Kibana, it says there is an error despite it being a valid API call.

Although the comments are not stored with the template in Elasticsearch. It would be helpful if Console would handle them gracefully.

The above simple example is based on when I was creating a custom index template using the ECS template as the base of my new one. I wanted to comment which fields were custom for easy (future) identification.

[elasticmachine]

Pinging @elastic/es-ui (Team:Elasticsearch UI)

[cjcenizal]

Although the comments are not stored with the template in Elasticsearch. It would be helpful if Console would handle them gracefully.

@a03nikki Is part of your request that Elasticsearch also store the comments? The reason I ask is that we already have a feature request open for supporting comments in the request body in Console (#11973), except it doesn't mention preserving these comments in Elasticsearch. If that's not part of your request then we can close this issue as a duplicate.

[a03nikki]

@cjcenizal : No, I was not intending to make the request to also store them in Elasticsearch.
I must have not been searching the right terms to find #11973. If that ticket will also handle the "Auto indent" functionality, then this can be closed as a duplicate.

[cjcenizal]

Closing in favor of #11973.