Updated documentation about `arduino-cli` integration options. (#2605)

* Fixed some examples

* Added example of integration by embedding golang

rpc/internal/get_version_example/main.go

+// This file is part of arduino-cli.
+//
+// Copyright 2024 ARDUINO SA (http://www.arduino.cc/)
+//
+// This software is released under the GNU General Public License version 3,
+// which covers the main part of arduino-cli.
+// The terms of this license can be found at:
+// https://www.gnu.org/licenses/gpl-3.0.en.html
+//
+// You can be released from the requirements of the above licenses by purchasing
+// a commercial license. Buying such a license is mandatory if you want to
+// modify or otherwise use the software for commercial activities involving the
+// Arduino software without disclosing the source code of your own applications.
+// To purchase a commercial license, send an email to license@arduino.cc.
+
+package main
+
+import (
+	"context"
+	"log"
+	"time"
+
+	rpc "github.com/arduino/arduino-cli/rpc/cc/arduino/cli/commands/v1"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+)
+
+func main() {
+	// Establish a connection with the gRPC server
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	conn, err := grpc.DialContext(ctx, "localhost:50051",
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+		grpc.WithBlock())
+	cancel()
+	if err != nil {
+		log.Println(err)
+		log.Fatal("error connecting to arduino-cli rpc server, you can start it by running `arduino-cli daemon`")
+	}
+	defer conn.Close()
+
+	// Create an instance of the gRPC clients.
+	cli := rpc.NewArduinoCoreServiceClient(conn)
+
+	// Now we can call various methods of the API...
+	versionResp, err := cli.Version(context.Background(), &rpc.VersionRequest{})
+	if err != nil {
+		log.Fatalf("Error getting version: %s", err)
+	}
+	log.Printf("arduino-cli version: %v", versionResp.GetVersion())
+}

rpc/internal/list_cores_example/main.go

+// This file is part of arduino-cli.
+//
+// Copyright 2024 ARDUINO SA (http://www.arduino.cc/)
+//
+// This software is released under the GNU General Public License version 3,
+// which covers the main part of arduino-cli.
+// The terms of this license can be found at:
+// https://www.gnu.org/licenses/gpl-3.0.en.html
+//
+// You can be released from the requirements of the above licenses by purchasing
+// a commercial license. Buying such a license is mandatory if you want to
+// modify or otherwise use the software for commercial activities involving the
+// Arduino software without disclosing the source code of your own applications.
+// To purchase a commercial license, send an email to license@arduino.cc.
+
+package main
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"log"
+
+	"github.com/arduino/arduino-cli/commands"
+	rpc "github.com/arduino/arduino-cli/rpc/cc/arduino/cli/commands/v1"
+	"github.com/sirupsen/logrus"
+)
+
+func main() {
+	// Create a new ArduinoCoreServer
+	srv := commands.NewArduinoCoreServer()
+
+	// Disable logging
+	logrus.SetOutput(io.Discard)
+
+	// Create a new instance in the server
+	ctx := context.Background()
+	resp, err := srv.Create(ctx, &rpc.CreateRequest{})
+	if err != nil {
+		log.Fatal("Error creating instance:", err)
+	}
+	instance := resp.GetInstance()
+
+	// Defer the destruction of the instance
+	defer func() {
+		if _, err := srv.Destroy(ctx, &rpc.DestroyRequest{Instance: instance}); err != nil {
+			log.Fatal("Error destroying instance:", err)
+		}
+		fmt.Println("Instance successfully destroyed")
+	}()
+
+	// Initialize the instance
+	initStream := commands.InitStreamResponseToCallbackFunction(ctx, func(r *rpc.InitResponse) error {
+		fmt.Println("INIT> ", r)
+		return nil
+	})
+	if err := srv.Init(&rpc.InitRequest{Instance: instance}, initStream); err != nil {
+		log.Fatal("Error during initialization:", err)
+	}
+
+	// Search for platforms and output the result
+	searchResp, err := srv.PlatformSearch(ctx, &rpc.PlatformSearchRequest{Instance: instance})
+	if err != nil {
+		log.Fatal("Error searching for platforms:", err)
+	}
+	for _, platformSummary := range searchResp.GetSearchOutput() {
+		installed := platformSummary.GetInstalledRelease()
+		meta := platformSummary.GetMetadata()
+		fmt.Printf("%30s %8s %s\n", meta.GetId(), installed.GetVersion(), installed.GetName())
+	}
+}