Allow use of "/" in Metrics Instrument Names

[aabmass]

• See recent spec change, Add "/" to valid characters for instrument names opentelemetry-specification#3684

And update the validation

opentelemetry-go/sdk/metric/meter.go

Lines 264 to 268 in 4242228

	for _, c := range name[1:] {
	if !isAlphanumeric(c) && c != '_' && c != '.' && c != '-' {
	return fmt.Errorf("%w: %s: must only contain [A-Za-z0-9_.-]", ErrInstrumentName, name)
	}
	}

Then update spec compliance matrix https://github.com/open-telemetry/opentelemetry-specification/blob/main/spec-compliance-matrix.md