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/asymkey/ssh_key_fingerprint.go

@@ -15,6 +15,7 @@ import (
 	"code.gitea.io/gitea/modules/util"
 
 	"golang.org/x/crypto/ssh"
+	"xorm.io/builder"
 )
 
 // ___________.__                                         .__        __
@@ -31,9 +32,7 @@ import (
 // checkKeyFingerprint only checks if key fingerprint has been used as public key,
 // it is OK to use same key as deploy key for multiple repositories/users.
 func checkKeyFingerprint(ctx context.Context, fingerprint string) error {
-	has, err := db.GetByBean(ctx, &PublicKey{
-		Fingerprint: fingerprint,
-	})
+	has, err := db.Exist[PublicKey](ctx, builder.Eq{"fingerprint": fingerprint})
 	if err != nil {
 		return err
 	} else if has {