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_test.go

@@ -28,7 +28,7 @@ import (
 
 // Initialize cache objects.
 func initCacheObjects(disk string, cacheMaxUse int) (*diskCache, error) {
-	return newdiskCache(disk, globalCacheExpiry, cacheMaxUse)
+	return newDiskCache(disk, 80, cacheMaxUse)
 }
 
 // inits diskCache struct for nDisks
@@ -109,7 +109,7 @@ func TestGetCacheMaxUse(t *testing.T) {
 		if err != nil {
 			t.Fatal(err)
 		}
-		d, err := initDiskCaches(fsDirs, globalCacheMaxUse, t)
+		d, err := initDiskCaches(fsDirs, 80, t)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -258,7 +258,7 @@ func TestDiskCacheMaxUse(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	d, err := initDiskCaches(fsDirs, globalCacheMaxUse, t)
+	d, err := initDiskCaches(fsDirs, 80, t)
 	if err != nil {
 		t.Fatal(err)
 	}