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/api-headers.go

@@ -40,7 +40,7 @@ func setCommonHeaders(w http.ResponseWriter) {
 	w.Header().Set(xhttp.ServerInfo, "MinIO/"+ReleaseTag)
 	// Set `x-amz-bucket-region` only if region is set on the server
 	// by default minio uses an empty region.
-	if region := globalServerConfig.GetRegion(); region != "" {
+	if region := globalServerRegion; region != "" {
 		w.Header().Set(xhttp.AmzBucketRegion, region)
 	}
 	w.Header().Set(xhttp.AcceptRanges, "bytes")