[client] Add Expose support to embed library (#5695)

* [client] Add Expose support to embed library

Add ability to expose local services via the NetBird reverse proxy
from embedded client code.

Introduce ExposeSession with a blocking Wait method that keeps
the session alive until the context is cancelled.

Extract ProtocolType with ParseProtocolType into the expose package
and use it across CLI and embed layers.

* Fix TestNewRequest assertion to use ProtocolType instead of int

* Add documentation for Request and KeepAlive in expose manager

* Refactor ExposeSession to pass context explicitly in Wait method

* Refactor ExposeSession Wait method to explicitly pass context

* Update client/embed/expose.go

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* Fix build

* Update client/embed/expose.go

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

---------

Co-authored-by: Viktor Liu <viktor@netbird.io>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
Co-authored-by: Viktor Liu <17948409+lixmal@users.noreply.github.com>

client/internal/expose/protocol.go

@@ -0,0 +1,40 @@
+package expose
+
+import (
+	"fmt"
+	"strings"
+)
+
+// ProtocolType represents the protocol used for exposing a service.
+type ProtocolType int
+
+const (
+	// ProtocolHTTP exposes the service as HTTP.
+	ProtocolHTTP ProtocolType = 0
+	// ProtocolHTTPS exposes the service as HTTPS.
+	ProtocolHTTPS ProtocolType = 1
+	// ProtocolTCP exposes the service as TCP.
+	ProtocolTCP ProtocolType = 2
+	// ProtocolUDP exposes the service as UDP.
+	ProtocolUDP ProtocolType = 3
+	// ProtocolTLS exposes the service as TLS.
+	ProtocolTLS ProtocolType = 4
+)
+
+// ParseProtocolType parses a protocol string into a ProtocolType.
+func ParseProtocolType(s string) (ProtocolType, error) {
+	switch strings.ToLower(s) {
+	case "http":
+		return ProtocolHTTP, nil
+	case "https":
+		return ProtocolHTTPS, nil
+	case "tcp":
+		return ProtocolTCP, nil
+	case "udp":
+		return ProtocolUDP, nil
+	case "tls":
+		return ProtocolTLS, nil
+	default:
+		return 0, fmt.Errorf("unsupported protocol %q: must be http, https, tcp, udp, or tls", s)
+	}
+}