Move Version function and code from global to toplevel (#1330)

* Move global code to toplevel package

* Move version function to toplevel package

* Update changelog

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

metric.go

@@ -0,0 +1,49 @@
+// 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 otel // import "go.opentelemetry.io/otel"
+
+import (
+	"go.opentelemetry.io/otel/internal/global"
+	"go.opentelemetry.io/otel/metric"
+)
+
+// Meter creates an implementation of the Meter interface from the global
+// MeterProvider. The instrumentationName must be the name of the library
+// providing instrumentation. This name may be the same as the instrumented
+// code only if that code provides built-in instrumentation. If the
+// instrumentationName is empty, then a implementation defined default name
+// will be used instead.
+//
+// This is short for MeterProvider().Meter(name)
+func Meter(instrumentationName string, opts ...metric.MeterOption) metric.Meter {
+	return GetMeterProvider().Meter(instrumentationName, opts...)
+}
+
+// GetMeterProvider returns the registered global meter provider.  If
+// none is registered then a default meter provider is returned that
+// forwards the Meter interface to the first registered Meter.
+//
+// Use the meter provider to create a named meter. E.g.
+//     meter := global.MeterProvider().Meter("example.com/foo")
+// or
+//     meter := global.Meter("example.com/foo")
+func GetMeterProvider() metric.MeterProvider {
+	return global.MeterProvider()
+}
+
+// SetMeterProvider registers `mp` as the global meter provider.
+func SetMeterProvider(mp metric.MeterProvider) {
+	global.SetMeterProvider(mp)
+}