[VOL-3860] redis client support in voltha-lib-go

redis client support has been added in this patch. There are two
types client `redis` and `redis-sentinel` to connect a redis instance.
redis-sentinel is required to be able to find the master redis
instance from a redis-sentinel process. See redis-sentinel usage
https://redis.io/topics/sentinel and
https://pkg.go.dev/github.com/go-redis/redis/v8#NewFailoverClient
for more information. If there is no need to have any failover
mechanism then the redis client type is the option to choose.

Change-Id: I997ed92115a9d565df632c6dd8184b9bab77b991
diff --git a/vendor/go.opentelemetry.io/otel/api/trace/context.go b/vendor/go.opentelemetry.io/otel/api/trace/context.go
new file mode 100644
index 0000000..0f330e3
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/trace/context.go
@@ -0,0 +1,55 @@
+// 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 trace
+
+import (
+	"context"
+)
+
+type traceContextKeyType int
+
+const (
+	currentSpanKey traceContextKeyType = iota
+	remoteContextKey
+)
+
+// ContextWithSpan creates a new context with a current span set to
+// the passed span.
+func ContextWithSpan(ctx context.Context, span Span) context.Context {
+	return context.WithValue(ctx, currentSpanKey, span)
+}
+
+// SpanFromContext returns the current span stored in the context.
+func SpanFromContext(ctx context.Context) Span {
+	if span, has := ctx.Value(currentSpanKey).(Span); has {
+		return span
+	}
+	return noopSpan{}
+}
+
+// ContextWithRemoteSpanContext creates a new context with a remote
+// span context set to the passed span context.
+func ContextWithRemoteSpanContext(ctx context.Context, sc SpanContext) context.Context {
+	return context.WithValue(ctx, remoteContextKey, sc)
+}
+
+// RemoteSpanContextFromContext returns the remote span context stored
+// in the context.
+func RemoteSpanContextFromContext(ctx context.Context) SpanContext {
+	if sc, ok := ctx.Value(remoteContextKey).(SpanContext); ok {
+		return sc
+	}
+	return EmptySpanContext()
+}