feat: Add Filter by Keyword

[Malloti]

This PR do some changes:

• Changes UI for better acessibility;
  • Limits the icons of the users and labels being filtered by 6;
• Adds Filter by Keyword;
  • Searches for cards with the ocurrency of the informed keyword;

Example video:

https://github.com/plankanban/planka/assets/65376487/921a8126-dba3-41a8-a27f-490424b0ac83

Related issues: #53, #706 Fix Closed PR: #707

[CLAassistant]

All committers have signed the CLA.

[meltyshev]

Hi! Thanks for working on this 🙏

We seem to have a problem that there are 2 PRs with a solution to the same issue. The other PR has more functionality: searching with regular expressions, adding members and labels from the search text. Also the layout is done in the same way as in the v2. But the CLA hasn't been signed there yet.