Add more linters to improve code readability (#19989)

Add nakedret, unconvert, wastedassign, stylecheck and nolintlint linters to improve code readability

- nakedret - https://github.com/alexkohler/nakedret - nakedret is a Go static analysis tool to find naked returns in functions greater than a specified function length.
- unconvert - https://github.com/mdempsky/unconvert - Remove unnecessary type conversions
- wastedassign - https://github.com/sanposhiho/wastedassign -  wastedassign finds wasted assignment statements.
- notlintlint -  Reports ill-formed or insufficient nolint directives
- stylecheck - https://staticcheck.io/docs/checks/#ST - keep style consistent
  - excluded: [ST1003 - Poorly chosen identifier](https://staticcheck.io/docs/checks/#ST1003) and [ST1005 - Incorrectly formatted error string](https://staticcheck.io/docs/checks/#ST1005)

models/auth/oauth2.go

@@ -123,7 +123,7 @@ func GetOAuth2ApplicationByClientID(ctx context.Context, clientID string) (app *
 	if !has {
 		return nil, ErrOAuthClientIDInvalid{ClientID: clientID}
 	}
-	return
+	return app, err
 }
 
 // GetOAuth2ApplicationByID returns the oauth2 application with the given id. Returns an error if not found.
@@ -143,7 +143,7 @@ func GetOAuth2ApplicationByID(ctx context.Context, id int64) (app *OAuth2Applica
 func GetOAuth2ApplicationsByUserID(ctx context.Context, userID int64) (apps []*OAuth2Application, err error) {
 	apps = make([]*OAuth2Application, 0)
 	err = db.GetEngine(ctx).Where("uid = ?", userID).Find(&apps)
-	return
+	return apps, err
 }
 
 // CreateOAuth2ApplicationOptions holds options to create an oauth2 application
@@ -300,7 +300,7 @@ func (code *OAuth2AuthorizationCode) GenerateRedirectURI(state string) (redirect
 	}
 	q.Set("code", code.Code)
 	redirect.RawQuery = q.Encode()
-	return
+	return redirect, err
 }
 
 // Invalidate deletes the auth code from the database to invalidate this code
@@ -430,7 +430,7 @@ func GetOAuth2GrantByID(ctx context.Context, id int64) (grant *OAuth2Grant, err
 	} else if !has {
 		return nil, nil
 	}
-	return
+	return grant, err
 }
 
 // GetOAuth2GrantsByUserID lists all grants of a certain user