Issue #615 - have PackageVariant set readiness gate on PackageRevisions

- PackageVariant controller now uses a readiness gate to allow
  a PackageRevision to complete its mutation pipeline before it
  is allowed to be proposed/approved
- refactored conversion of Kptfiles to YAML since readiness condition
  information is stored in the package Kptfile
  - unified all cases to the same kyaml/yaml-based method
    (KptFile.ToYamlString() and ToYamlString(*fn.KubeObject))
  - this ensures consistency in the YAML (indentation, field order etc.)
  - and reduces the chances of Git conflicts when setting and updating
    readiness conditions
- added more info to error message in case of Git conflict when applying
  a patch

nephio-project/nephio#615

pkg/task/generictaskhandler.go

@@ -18,6 +18,7 @@ import (
 	"context"
 	"fmt"
 
+	sdkfn "github.com/GoogleContainerTools/kpt-functions-sdk/go/fn"
 	api "github.com/nephio-project/porch/api/porch/v1alpha1"
 	configapi "github.com/nephio-project/porch/api/porchconfig/v1alpha1"
 	"github.com/nephio-project/porch/internal/kpt/builtins"
@@ -527,6 +528,17 @@ func healConfig(old, new map[string]string) (map[string]string, error) {
 
 	healed := out.output.Contents
 
+	var kptfileKubeObject *sdkfn.KubeObject
+	if kptfileKubeObject, err = sdkfn.ParseKubeObject([]byte(healed[kptfile.KptFileName])); err != nil {
+		return nil, err
+	}
+
+	kptfileYaml, err := kptfile.ToYamlString(kptfileKubeObject)
+	if err != nil {
+		return nil, err
+	}
+	healed[kptfile.KptFileName] = kptfileYaml
+
 	for k, v := range extra {
 		healed[k] = v
 	}