speed up startup sequence for all operations (#14148)

This speed-up is intended for faster startup times
for almost all MinIO operations. Changes here are

- Drives are not re-read for 'format.json' on a regular
  basis once read during init is remembered and refreshed
  at 5 second intervals.

- Do not do O_DIRECT tests on drives with existing 'format.json'
  only fresh setups need this check.

- Parallelize initializing erasureSets for multiple sets.

- Avoid re-reading format.json when migrating 'format.json'
  from really old V1->V2->V3

- Keep a copy of local drives for any given server in memory
  for a quick lookup.

internal/ioutil/ioutil.go

@@ -238,10 +238,7 @@ func SameFile(fi1, fi2 os.FileInfo) bool {
 	if fi1.Mode() != fi2.Mode() {
 		return false
 	}
-	if fi1.Size() != fi2.Size() {
-		return false
-	}
-	return true
+	return fi1.Size() == fi2.Size()
 }
 
 // DirectioAlignSize - DirectIO alignment needs to be 4K. Defined here as

internal/ioutil/read_file.go

@@ -19,11 +19,33 @@ package ioutil
 
 import (
 	"io"
+	"io/fs"
 	"os"
 
 	"github.com/minio/minio/internal/disk"
 )
 
+// ReadFileWithFileInfo reads the named file and returns the contents.
+// A successful call returns err == nil, not err == EOF.
+// Because ReadFile reads the whole file, it does not treat an EOF from Read
+// as an error to be reported, additionall returns os.FileInfo
+func ReadFileWithFileInfo(name string) ([]byte, fs.FileInfo, error) {
+	f, err := os.Open(name)
+	if err != nil {
+		return nil, nil, err
+	}
+	defer f.Close()
+
+	st, err := f.Stat()
+	if err != nil {
+		return nil, nil, err
+	}
+
+	dst := make([]byte, st.Size())
+	_, err = io.ReadFull(f, dst)
+	return dst, st, err
+}
+
 // ReadFile reads the named file and returns the contents.
 // A successful call returns err == nil, not err == EOF.
 // Because ReadFile reads the whole file, it does not treat an EOF from Read