Migrate config to KV data format (#8392)

- adding oauth support to MinIO browser (#8400) by @kanagaraj
- supports multi-line get/set/del for all config fields
- add support for comments, allow toggle
- add extensive validation of config before saving
- support MinIO browser to support proper claims, using STS tokens
- env support for all config parameters, legacy envs are also
  supported with all documentation now pointing to latest ENVs
- preserve accessKey/secretKey from FS mode setups
- add history support implements three APIs
  - ClearHistory
  - RestoreHistory
  - ListHistory
- add help command support for each config parameters
- all the bug fixes after migration to KV, and other bug
  fixes encountered during testing.

cmd/utils.go

@@ -38,6 +38,7 @@ import (
 	xhttp "github.com/minio/minio/cmd/http"
 	"github.com/minio/minio/cmd/logger"
 	"github.com/minio/minio/pkg/handlers"
+	iampolicy "github.com/minio/minio/pkg/iam/policy"
 
 	humanize "github.com/dustin/go-humanize"
 	"github.com/gorilla/mux"
@@ -487,3 +488,7 @@ func getMinioMode() string {
 	}
 	return mode
 }
+
+func iamPolicyName() string {
+	return globalOpenIDConfig.ClaimPrefix + iampolicy.PolicyName
+}