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/interfaces/interfaces.go

@@ -0,0 +1,54 @@
+// Package interfaces provides shared interfaces used by both the main redis package
+// and the hitless upgrade package to avoid circular dependencies.
+package interfaces
+
+import (
+	"context"
+	"net"
+	"time"
+)
+
+// NotificationProcessor is (most probably) a push.NotificationProcessor
+// forward declaration to avoid circular imports
+type NotificationProcessor interface {
+	RegisterHandler(pushNotificationName string, handler interface{}, protected bool) error
+	UnregisterHandler(pushNotificationName string) error
+	GetHandler(pushNotificationName string) interface{}
+}
+
+// ClientInterface defines the interface that clients must implement for hitless upgrades.
+type ClientInterface interface {
+	// GetOptions returns the client options.
+	GetOptions() OptionsInterface
+
+	// GetPushProcessor returns the client's push notification processor.
+	GetPushProcessor() NotificationProcessor
+}
+
+// OptionsInterface defines the interface for client options.
+// Uses an adapter pattern to avoid circular dependencies.
+type OptionsInterface interface {
+	// GetReadTimeout returns the read timeout.
+	GetReadTimeout() time.Duration
+
+	// GetWriteTimeout returns the write timeout.
+	GetWriteTimeout() time.Duration
+
+	// GetNetwork returns the network type.
+	GetNetwork() string
+
+	// GetAddr returns the connection address.
+	GetAddr() string
+
+	// IsTLSEnabled returns true if TLS is enabled.
+	IsTLSEnabled() bool
+
+	// GetProtocol returns the protocol version.
+	GetProtocol() int
+
+	// GetPoolSize returns the connection pool size.
+	GetPoolSize() int
+
+	// NewDialer returns a new dialer function for the connection.
+	NewDialer() func(context.Context) (net.Conn, error)
+}