Default view should not be required when other views passed

[MrAlias]

Description

If a user passes a view to the MeterProvider during creation and an instrument not matching that view measures values it is not exported. A user is required to pass the default view as well as their custom view to ensure the default behavior on unmatched views.

This is contrary to the specification:

• If the MeterProvider has one or more View(s) registered:
  • [...]
  • If the Instrument could not match with any of the registered View(s), the
    SDK SHOULD enable the instrument using the default aggregation and temporality.
    Users can configure match-all Views using Drop aggregation
    to disable instruments by default.

Environment

• Go Version: 1.19
• opentelemetry-go version: 35019d3

Steps To Reproduce

main.go:

package main

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/signal"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"

	otelprom "go.opentelemetry.io/otel/exporters/prometheus"
	"go.opentelemetry.io/otel/sdk/metric"
	"go.opentelemetry.io/otel/sdk/metric/view"
)

func main() {
	ctx := context.Background()

	exporter := otelprom.New()
	v, err := view.New(
		view.MatchInstrumentName("unmatched-name"),
		view.WithRename("bar"),
	)
	if err != nil {
		log.Fatal(err)
	}

	provider := metric.NewMeterProvider(metric.WithReader(exporter, v))
	meter := provider.Meter("example")

	go serveMetrics(exporter.Collector)

	counter, err := meter.SyncFloat64().Counter("foo")
	if err != nil {
		log.Fatal(err)
	}
	counter.Add(ctx, 5)

	ctx, _ = signal.NotifyContext(ctx, os.Interrupt)
	<-ctx.Done()
}

func serveMetrics(collector prometheus.Collector) {
	registry := prometheus.NewRegistry()
	err := registry.Register(collector)
	if err != nil {
		fmt.Printf("error registering collector: %v", err)
		return
	}

	log.Printf("serving metrics at localhost:2222/metrics")
	http.Handle("/metrics", promhttp.HandlerFor(registry, promhttp.HandlerOpts{}))
	err = http.ListenAndServe(":2222", nil)
	if err != nil {
		fmt.Printf("error serving http: %v", err)
		return
	}
}

go.mod:

go 1.18

require (
	github.com/prometheus/client_golang v1.13.0
	go.opentelemetry.io/otel v1.10.0
	go.opentelemetry.io/otel/exporters/prometheus v0.31.0
	go.opentelemetry.io/otel/metric v0.32.0
	go.opentelemetry.io/otel/sdk v1.10.0
	go.opentelemetry.io/otel/sdk/metric v0.32.0
)

require (
	github.com/beorn7/perks v1.0.1 // indirect
	github.com/cespare/xxhash/v2 v2.1.2 // indirect
	github.com/go-logr/logr v1.2.3 // indirect
	github.com/go-logr/stdr v1.2.2 // indirect
	github.com/golang/protobuf v1.5.2 // indirect
	github.com/matttproud/golang_protobuf_extensions v1.0.1 // indirect
	github.com/prometheus/client_model v0.2.0 // indirect
	github.com/prometheus/common v0.37.0 // indirect
	github.com/prometheus/procfs v0.8.0 // indirect
	go.opentelemetry.io/otel/trace v1.10.0 // indirect
	golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a // indirect
	google.golang.org/protobuf v1.28.1 // indirect
)

$ go run .
2022/09/22 09:08:00 serving metrics at localhost:2222/metrics

# Returns nothing.
$ curl localhost:2222/metrics

Expected behavior

$ curl localhost:2222/metrics
# HELP foo
# TYPE foo counter
foo 5

[MrAlias]

Verified the changes proposed in #3237 resolve this issue based on the provided example.