feat: Reporter for OTel Metrics

[trentm]

With this change the APM agent adds support for using OTel Metrics in two ways:

1. The @opentelemetry/api package is instrumented so that usage of
   .metrics.getMeterProvider(...) will use one provided by the APM agent,
   if the user hasn't explicitly provided one of their own. This implementation
   uses a version of the OTel Metrics SDK included with the APM agent. It
   is configured to sent metrics to APM server by default. This allows a user
   to use the OTel Metrics API and get metrics set to APM server without any
   configuration.
2. Alternatively, the @opentelemetry/sdk-metrics package is instrumented so
   that when a user creates a MeterProvider, the APM agent will added a
   MetricReader that sends metrics to APM server. This allows a user to
   configure metrics as they wish using the OTel Metrics SDK and then
   automatically get those metrics sent to APM server.

Closes: #2954
Refs: elastic/apm#691
Refs: elastic/apm#742 (spec PR)

[apmmachine]

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• Start Time: 2023-03-29T22:08:55.154+0000

• Duration: 21 min 21 sec

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