[task scheduler] Move files from build_scheduler/ to task_scheduler/

task_scheduler/go/db/cache.go

 package db
 
 import (
         "fmt"
         "sync"
         "time"
 
         "github.com/skia-dev/glog"
 )
 
@@ skipping 224 matching lines @@
 func NewTaskCache(db DB, timePeriod time.Duration) (TaskCache, error) {
         tc := &taskCache{
                 db:         db,
                 timePeriod: timePeriod,
         }
         if err := tc.reset(); err != nil {
                 return nil, err
         }
         return tc, nil
 }