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/gateway/hdfs/gateway-hdfs.go

@@ -79,7 +79,7 @@ ENVIRONMENT VARIABLES:
      MINIO_CACHE_DRIVES: List of mounted drives or directories delimited by ";".
      MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";".
      MINIO_CACHE_EXPIRY: Cache expiry duration in days.
-     MINIO_CACHE_MAXUSE: Maximum permitted usage of the cache in percentage (0-100).
+     MINIO_CACHE_QUOTA: Maximum permitted usage of the cache in percentage (0-100).
 
 EXAMPLES:
   1. Start minio gateway server for HDFS backend.
@@ -93,7 +93,7 @@ EXAMPLES:
      {{.Prompt}} {{.EnvVarSetCommand}} MINIO_CACHE_DRIVES{{.AssignmentOperator}}"/mnt/drive1;/mnt/drive2;/mnt/drive3;/mnt/drive4"
      {{.Prompt}} {{.EnvVarSetCommand}} MINIO_CACHE_EXCLUDE{{.AssignmentOperator}}"bucket1/*;*.png"
      {{.Prompt}} {{.EnvVarSetCommand}} MINIO_CACHE_EXPIRY{{.AssignmentOperator}}40
-     {{.Prompt}} {{.EnvVarSetCommand}} MINIO_CACHE_MAXUSE{{.AssignmentOperator}}80
+     {{.Prompt}} {{.EnvVarSetCommand}} MINIO_CACHE_QUOTA{{.AssignmentOperator}}80
      {{.Prompt}} {{.HelpName}} hdfs://namenode:8200
 `