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/config/bool-flag.go

@@ -19,6 +19,8 @@ package config
 import (
 	"encoding/json"
 	"fmt"
+	"strconv"
+	"strings"
 )
 
 // BoolFlag - wrapper bool type.
@@ -54,16 +56,35 @@ func (bf *BoolFlag) UnmarshalJSON(data []byte) (err error) {
 	return err
 }
 
+// FormatBool prints stringified version of boolean.
+func FormatBool(b bool) string {
+	if b {
+		return "on"
+	}
+	return "off"
+}
+
+// ParseBool returns the boolean value represented by the string.
+// It accepts 1, t, T, TRUE, true, True, 0, f, F, FALSE, false, False.
+// Any other value returns an error.
+func ParseBool(str string) (bool, error) {
+	switch str {
+	case "1", "t", "T", "true", "TRUE", "True", "on", "ON", "On":
+		return true, nil
+	case "0", "f", "F", "false", "FALSE", "False", "off", "OFF", "Off":
+		return false, nil
+	}
+	if strings.EqualFold(str, "enabled") {
+		return true, nil
+	}
+	if strings.EqualFold(str, "disabled") {
+		return false, nil
+	}
+	return false, fmt.Errorf("ParseBool: parsing '%s': %s", str, strconv.ErrSyntax)
+}
+
 // ParseBoolFlag - parses string into BoolFlag.
 func ParseBoolFlag(s string) (bf BoolFlag, err error) {
-	switch s {
-	case "on":
-		bf = true
-	case "off":
-		bf = false
-	default:
-		err = fmt.Errorf("invalid value ‘%s’ for BoolFlag", s)
-	}
-
-	return bf, err
+	b, err := ParseBool(s)
+	return BoolFlag(b), err
 }