feat: RESP3 notifications support & Hitless notifications handling [CAE-1088] & [CAE-1072] (#3418)

- Adds support for handling push notifications with RESP3. 
- Using this support adds handlers for hitless upgrades.

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Hristo Temelski <hristo.temelski@redis.com>

internal/log.go

@@ -7,20 +7,27 @@ import (
 	"os"
 )
 
+// TODO (ned): Revisit logging
+// Add more standardized approach with log levels and configurability
+
 type Logging interface {
 	Printf(ctx context.Context, format string, v ...interface{})
 }
 
-type logger struct {
+type DefaultLogger struct {
 	log *log.Logger
 }
 
-func (l *logger) Printf(ctx context.Context, format string, v ...interface{}) {
+func (l *DefaultLogger) Printf(ctx context.Context, format string, v ...interface{}) {
 	_ = l.log.Output(2, fmt.Sprintf(format, v...))
 }
 
+func NewDefaultLogger() Logging {
+	return &DefaultLogger{
+		log: log.New(os.Stderr, "redis: ", log.LstdFlags|log.Lshortfile),
+	}
+}
+
 // Logger calls Output to print to the stderr.
 // Arguments are handled in the manner of fmt.Print.
-var Logger Logging = &logger{
-	log: log.New(os.Stderr, "redis: ", log.LstdFlags|log.Lshortfile),
-}
+var Logger Logging = NewDefaultLogger()