Remove GetByBean method because sometimes it's danger when query condition parameter is zero and also introduce new generic methods (#28220)

The function `GetByBean` has an obvious defect that when the fields are
empty values, it will be ignored. Then users will get a wrong result
which is possibly used to make a security problem.

To avoid the possibility, this PR removed function `GetByBean` and all
references.
And some new generic functions have been introduced to be used.

The recommand usage like below.

```go
// if query an object according id
obj, err := db.GetByID[Object](ctx, id)
// query with other conditions
obj, err := db.Get[Object](ctx, builder.Eq{"a": a, "b":b})
```

models/perm/access/access.go

@@ -13,6 +13,8 @@ import (
 	"code.gitea.io/gitea/models/perm"
 	repo_model "code.gitea.io/gitea/models/repo"
 	user_model "code.gitea.io/gitea/models/user"
+
+	"xorm.io/builder"
 )
 
 // Access represents the highest access level of a user to the repository. The only access type
@@ -51,9 +53,11 @@ func accessLevel(ctx context.Context, user *user_model.User, repo *repo_model.Re
 		return perm.AccessModeOwner, nil
 	}
 
-	a := &Access{UserID: userID, RepoID: repo.ID}
-	if has, err := db.GetByBean(ctx, a); !has || err != nil {
+	a, exist, err := db.Get[Access](ctx, builder.Eq{"user_id": userID, "repo_id": repo.ID})
+	if err != nil {
 		return mode, err
+	} else if !exist {
+		return mode, nil
 	}
 	return a.Mode, nil
 }