Add Support for Cache and S3 related metrics in Prometheus endpoint (#8591)

This PR adds support below metrics

- Cache Hit Count
- Cache Miss Count
- Data served from Cache (in Bytes)
- Bytes received from AWS S3
- Bytes sent to AWS S3
- Number of requests sent to AWS S3

Fixes #8549

cmd/tree-walk_test.go

@@ -93,7 +93,7 @@ func testTreeWalkPrefix(t *testing.T, listDir ListDirFunc) {
 
 	// Check if all entries received on the channel match the prefix.
 	for res := range twResultCh {
-		if !hasPrefix(res.entry, prefix) {
+		if !HasPrefix(res.entry, prefix) {
 			t.Errorf("Entry %s doesn't match prefix %s", res.entry, prefix)
 		}
 	}