…etricutil package

Add the service instance id to the resource attributes to prevent
downstream OTEL processors and exporters from thinking that the CLI
invocations are a single process that keeps restarting. The unique id
can be removed through downstream aggregation to prevent cardinality
issues, but we need some way to tell OTEL that it shouldn't reset the
counters.

Move the check for the experimental flag to its own package and then use
that invocation to prevent creating exporters so metrics are disabled
completely. This makes it so we don't have to check for the experimental
flag in every place we add metrics until we decide to make metrics
stable in general.

This also moves the OTEL initialization to a `util/metricutil` package
to be more consistent with the existing util naming and to differentiate
it from the upstream `metric` name. Using both `metrics` and `metric` as
import names was confusing since `metric` was an upstream dependency and
`metrics` was a local utility. `metricutil` matches with the existing
utilities and makes clear that it isn't a spelling mistake.

The record version metric has been removed since we weren't planning on
keeping that metric anyway and most of the information is now included
in the instrumentation library name and version. That function is
included as a utility in the `otel/sdk/metric` package to retrieve the
appropriate meter from the meter provider.

Signed-off-by: Jonathan A. Sternberg <[email protected]>