[FR] Filter Kanban board by Sprint

[broskees]

> READ THIS FIRST!: We recently announced Taiga plans for the future and they greatly affect how we manage this repository and the current Taiga 6 release. Check it here.chore: readme announce taiga-next

Please describe the problem / need you are trying to solve.

I'm always frustrated when I try to use the kanban module with a scrum project, but can see the backlog and such in the kanban board and have no way to filter it out.

Describe the feature or the improvement you'd like and what are you trying to achieve.

I'd love to have sprint related filters. Like filter by Sprint.

Describe alternatives you've considered

Add new statuses for when things are in the backlog and hide that status. Not ideal at all.

Additional context