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.

docs/erasure/storage-class/README.md

@@ -62,12 +62,14 @@ Default value for `REDUCED_REDUNDANCY` storage class is `2`.
 
 The format to set storage class environment variables is as follows
 
+`MINIO_STORAGE_CLASS_STATE=on`
 `MINIO_STORAGE_CLASS_STANDARD=EC:parity`
 `MINIO_STORAGE_CLASS_RRS=EC:parity`
 
 For example, set `MINIO_STORAGE_CLASS_RRS` parity 2 and `MINIO_STORAGE_CLASS_STANDARD` parity 3
 
 ```sh
+export MINIO_STORAGE_CLASS_STATE=on
 export MINIO_STORAGE_CLASS_STANDARD=EC:3
 export MINIO_STORAGE_CLASS_RRS=EC:2
 ```
@@ -77,7 +79,7 @@ more details.
 
 *Note*
 
-- If `STANDARD` storage class is set via environment variables or `mc admin config` get/set commands, and `x-amz-storage-class` is not present in request metadata, MinIO server will 
+- If `STANDARD` storage class is set via environment variables or `mc admin config` get/set commands, and `x-amz-storage-class` is not present in request metadata, MinIO server will
 apply `STANDARD` storage class to the object. This means the data and parity disks will be used as set in `STANDARD` storage class.
 
 - If storage class is not defined before starting MinIO server, and subsequent PutObject metadata field has `x-amz-storage-class` present
@@ -108,4 +110,4 @@ if err != nil {
 	log.Fatalln(err)
 }
 log.Println("Uploaded", "my-objectname", " of size: ", n, "Successfully.")
-```
+```