How to use global meter provider to register multiple providers

[RupakVeerla]

Problem Statement

Currently global.SetMeterProvider supports only one meter provider at a time, while according to our requirement, we need both Stackdriver and Prometheus metric exporter.

Proposed Solution

Is it possible to use multiple exporters with global.SetMeterProvider?

Alternatives

Is there any alternative to global.SetMeterProvider?

Additional Context

Prometheus exporter

	exporter, err := prometheus.New(config, c)
	if err != nil {
		return nil, err
	}

	global.SetMeterProvider(exporter.MeterProvider())

Stackdriver exporter

func InstallNewPipeline(opts []Option, popts ...controller.Option) (*controller.Controller, error) {
	pusher, err := NewExportPipeline(opts, popts...)
	if err != nil {
		return nil, err
	}
	global.SetMeterProvider(pusher)
	return pusher, err
}