Use db.Find instead of writing methods for every object (#28084)

For those simple objects, it's unnecessary to write the find and count
methods again and again.

models/auth/oauth2_list.go

@@ -0,0 +1,32 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package auth
+
+import (
+	"code.gitea.io/gitea/models/db"
+
+	"xorm.io/builder"
+)
+
+type FindOAuth2ApplicationsOptions struct {
+	db.ListOptions
+	// OwnerID is the user id or org id of the owner of the application
+	OwnerID int64
+	// find global applications, if true, then OwnerID will be igonred
+	IsGlobal bool
+}
+
+func (opts FindOAuth2ApplicationsOptions) ToConds() builder.Cond {
+	conds := builder.NewCond()
+	if opts.IsGlobal {
+		conds = conds.And(builder.Eq{"uid": 0})
+	} else if opts.OwnerID != 0 {
+		conds = conds.And(builder.Eq{"uid": opts.OwnerID})
+	}
+	return conds
+}
+
+func (opts FindOAuth2ApplicationsOptions) ToOrders() string {
+	return "id DESC"
+}