Added API name to request metadata

[delvedor]

This is very useful if you need to filter logging and you don't want to use regular expressions.

Usage:

const { Client } = require('@elastic/elasticsearch')
const client = new Client({
  node: 'http://localhost:9200'
})

client.on('response', (err, { meta }) => {
  if (err) {
    logger.error(err)
  } else {
    logger.info(`Api called: ${meta.request.options.api}`) // 'elasticsearch.info'
  }
})

client.info(console.log)

[trentm]

I like this feature. I think it would make matching of ES API endpoints faster in the Node.js APM Agent. However, after some discussion with the APM team there was a desire to have the config for selecting ES API endpoints for request body capture be shared between languages. This "api" name isn't a common language between all the ES clients. The only common mechanism for matching ES API endpoints is the ES URL path, i.e. what the current Node.js APM Agent is already using to match.

So if the Node.js APM Agent was the only use case for this "api" name, you might want to consider not merging this for now.