labwc: Cascading window style & full screen launcher

[humaidq-tii]

Description of changes

This sets a cascading window policy, so not all windows are launched center of screen.

It also makes the launcher use the full screen, now it can better support small devices too. This improves usability.

Tidy up launcher names and descriptions, and also change styling for date/time to 24h time as per previous requirement.

Checklist for things done

• Summary of the proposed changes in the PR description
• More detailed description in the commit message(s)
• Commits are squashed into relevant entities - avoid a lot of minimal dev time commits in the PR
• Contribution guidelines followed
• Ghaf documentation updated with the commit - https://tiiuae.github.io/ghaf/
• PR linked to architecture documentation and requirement(s) (ticket id)
• Test procedure described (or includes tests). Select one or more:
  • Tested on Lenovo X1 x86_64
  • Tested on Jetson Orin NX or AGX aarch64
  • Tested on Polarfire riscv64
• Author has run make-checks and it passes
• All automatic Github Action checks pass - see actions
• Author has added reviewers and removed PR draft status
• Change requires full re-installation: No
• Change can be updated with nixos-rebuild ... switch Yes, gui-vm needs to be reloaded

Instructions for Testing

• List all targets that this applies to: X1, orin
• Is this a new feature: Not really, just UI/UX improvement
  • List the test steps to verify:
    • Boot, check application launcher, should show full screen with no issues. 6 columns instead of previously 5.
    • The eww widgets should have proper padding.
    • Window placement should follow cascade policy (sometimes it is hard to notice, also chromium doesn't respect this but it is okay).
• If it is an improvement how does it impact existing functionality?
  • Should improve usability, launcher items should be more ergonomic to access.
  • Also windows would follow cascade placement, so it improve user experience.