Move db related basic functions to models/db (#17075)

* Move db related basic functions to models/db

* Fix lint

* Fix lint

* Fix test

* Fix lint

* Fix lint

* revert unnecessary change

* Fix test

* Fix wrong replace string

* Use *Context

* Correct committer spelling and fix wrong replaced words

Co-authored-by: zeripath <art27@cantab.net>

modules/indexer/stats/indexer_test.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/models/db"
 	"code.gitea.io/gitea/modules/setting"
 
 	"gopkg.in/ini.v1"
@@ -18,11 +19,11 @@ import (
 )
 
 func TestMain(m *testing.M) {
-	models.MainTest(m, filepath.Join("..", "..", ".."))
+	db.MainTest(m, filepath.Join("..", "..", ".."))
 }
 
 func TestRepoStatsIndex(t *testing.T) {
-	assert.NoError(t, models.PrepareTestDatabase())
+	assert.NoError(t, db.PrepareTestDatabase())
 	setting.Cfg = ini.Empty()
 
 	setting.NewQueueService()