Add option to filter board cards by labels and assignees (#31999)

Works in both organization and repository project boards

Fixes #21846

Replaces #21963
Replaces #27117
 

![image](https://github.com/user-attachments/assets/1837ace8-3de2-444f-a153-e166bd0da2c0)

**Note** that implementation was made intentionally to work same as in
issue list so that URL can be bookmarked for quick access with
predefined filters in URL

models/issues/issue_search.go

@@ -54,6 +54,19 @@ type IssuesOptions struct { //nolint
 	User           *user_model.User           // issues permission scope
 }
 
+// Copy returns a copy of the options.
+// Be careful, it's not a deep copy, so `IssuesOptions.RepoIDs = {...}` is OK while `IssuesOptions.RepoIDs[0] = ...` is not.
+func (o *IssuesOptions) Copy(edit ...func(options *IssuesOptions)) *IssuesOptions {
+	if o == nil {
+		return nil
+	}
+	v := *o
+	for _, e := range edit {
+		e(&v)
+	}
+	return &v
+}
+
 // applySorts sort an issues-related session based on the provided
 // sortType string
 func applySorts(sess *xorm.Session, sortType string, priorityRepoID int64) {