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/disk-cache.go

@@ -409,7 +409,12 @@ func newCache(config cache.Config) ([]*diskCache, bool, error) {
 			return nil, false, errors.New("Atime support required for disk caching")
 		}
 
-		cache, err := newdiskCache(dir, config.Expiry, config.MaxUse)
+		quota := config.MaxUse
+		if quota == 0 {
+			quota = config.Quota
+		}
+
+		cache, err := newDiskCache(dir, config.Expiry, quota)
 		if err != nil {
 			return nil, false, err
 		}