Support export of Helidon metrics via OpenTelemetry metrics exporter(s)

[tjquinno]

Helidon Version: 4.x

Enhancement Description

Provide a simple way for users to have Helidon transmit data for metrics managed using the Helidon metrics API using the OpenTelemetry OTLP protocol.

[tjquinno]

(copied from the comment first written on the original epic issue)

After some team discussions, we will provide the third item listed in the description--OTLP output from Helidon metrics--by using the existing Micrometer OpenTelemetry meter registry and the Micrometer-to-OTLP bridge io.micrometer:micrometer-registry-otlp which emits OTLP.

We will make changes in Helidon to allow Helidon config to drive the settings used by the bridge.

The existing metrics observer will remain unchanged, as will support for the /observe/metrics endpoint.