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.

pkg/quick/encoding.go

@@ -187,10 +187,6 @@ func loadFileConfig(filename string, v interface{}) error {
 		fileData = []byte(strings.Replace(string(fileData), "\r\n", "\n", -1))
 	}
 
-	if err = checkDupJSONKeys(string(fileData)); err != nil {
-		return err
-	}
-
 	// Unmarshal file's content
 	return toUnmarshaller(filepath.Ext(filename))(fileData, v)
 }