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

task_scheduler/go/db/memory.go

 package db
 
 import (
         "fmt"
         "sort"
         "sync"
         "time"
 
         "go.skia.org/infra/go/util"
 
@@ skipping 100 matching lines @@
 }
 
 // NewInMemoryDB returns an extremely simple, inefficient, in-memory DB
 // implementation.
 func NewInMemoryDB() DB {
         db := &inMemoryDB{
                 tasks: map[string]*Task{},
         }
         return db
 }