cloudapi: Add support for GCP as upload target

Add support for GCP as an upload target to the internal API.

Extend the cloudapi to allow GCP as an upload target in the compose
request. Regenerate the cloudapi go code. Added GCP-specific upload
result component in the API definition, similar to AWS. It is not yet
used, but it will be once returning a target-specific result from
worker is supported.

Add support for GCP upload target to the worker job implementation.

Signed-off-by: Tomas Hozza <thozza@redhat.com>

internal/target/gcp_target.go

@@ -0,0 +1,16 @@
+package target
+
+type GCPTargetOptions struct {
+	Filename          string   `json:"filename"`
+	Region            string   `json:"region"`
+	Os                string   `json:"os"` // not exposed in cloudapi for now
+	Bucket            string   `json:"bucket"`
+	Object            string   `json:"object"`
+	ShareWithAccounts []string `json:"shareWithAccounts"`
+}
+
+func (GCPTargetOptions) isTargetOptions() {}
+
+func NewGCPTarget(options *GCPTargetOptions) *Target {
+	return newTarget("org.osbuild.gcp", options)
+}

internal/target/target.go

@@ -3,9 +3,10 @@ package target
 import (
 	"encoding/json"
 	"errors"
+	"time"
+
 	"github.com/google/uuid"
 	"github.com/osbuild/osbuild-composer/internal/common"
-	"time"
 )
 
 type Target struct {
@@ -68,6 +69,8 @@ func UnmarshalTargetOptions(targetName string, rawOptions json.RawMessage) (Targ
 		options = new(AzureTargetOptions)
 	case "org.osbuild.aws":
 		options = new(AWSTargetOptions)
+	case "org.osbuild.gcp":
+		options = new(GCPTargetOptions)
 	case "org.osbuild.local":
 		options = new(LocalTargetOptions)
 	case "org.osbuild.koji":