Combine the Push and Pull metric controllers (#1378)

* Push->basic

* Repackage

* Rename away from push

* Make exporter optional; export from a separate goroutine

* Move pull_test into controller_test

* Precommit pass

* New OTLP/Prom example

* Precommit

* Fix the example

* Shorten the example

* Test starting controller w/o exporter

* Test export timeout

* Remove ancient example & lint

* go.mod revert & tidy

* Comments

* Tidy a diff

* Tidy a diff

* Move export kind selector in the new example

* Split this test into its original parts

* Reduce diff size

* Changelog

* Remove extra Add/Done pair

* Remove unused stopCh param; document the Stop behavior

* Typo

* Use ctx

* Missed v0.15

* Apply PR feedback

* Precommit pass

* 0.14 -> 0.15 in new file

* Remove diff chunk markers

* Fix OTLP example

* Upstream

* dashpole comments

* aneurysm9 feedback

* Tidy go.sum

sdk/metric/controller/basic/config_test.go

@@ -0,0 +1,37 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package basic
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"go.opentelemetry.io/otel/label"
+	"go.opentelemetry.io/otel/sdk/resource"
+)
+
+func TestWithResource(t *testing.T) {
+	r := resource.NewWithAttributes(label.String("A", "a"))
+
+	c := &Config{}
+	WithResource(r).Apply(c)
+	assert.Equal(t, r.Equivalent(), c.Resource.Equivalent())
+
+	// Ensure overwriting works.
+	c = &Config{Resource: &resource.Resource{}}
+	WithResource(r).Apply(c)
+	assert.Equal(t, r.Equivalent(), c.Resource.Equivalent())
+}