Add security context indicator to COSMIC

[nesteroff]

Description of Changes

This adds an initial version of a patch to the COSMIC compositor that enables setting different window frame colors based on the security context attached to the Wayland connection. This allows applications running in different AppVMs to have different window frame colors similar to how it works in Labwc.

Type of Change

• New Feature
• Bug Fix
• Improvement / Refactor

Related Issues / Tickets

Checklist

• Clear summary in PR description
• Detailed and meaningful commit message(s)
• Commits are logically organized and squashed if appropriate
• Contribution guidelines followed
• Ghaf documentation updated with the commit - https://tiiuae.github.io/ghaf/
• 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

Testing Instructions

Applicable Targets

• Orin AGX aarch64
• Orin NX aarch64
• Lenovo X1 x86_64
• Dell Latitude x86_64

Installation Method

• Requires full re-installation
• Can be updated with nixos-rebuild ... switch
• Other:

Test Steps To Verify:

1. Build a Lenovo X1 image with COSMIC enabled (lenovo-x1-gen11-cosmic-debug).
2. Run different application and make sure they have correct window frame colors.

[milva-unikie]

Tested on Lenovo-X1 Cosmic (new image)

• All apps running in the VMs have correctly colored border
• Test-automation passes

Tested on Lenovo-X1 Labwc (nixos-rebuild switch)

• Quick sanity check - all good
• Test-automation passes

Notes

• The color scheme may need some rethinking in the future. Currently the business-vm border green is quite close to the active window border green.

[kajusnau]

Seems to work great!
As Milla noted, the appearance will have to be adjusted in the future, but that will be a minor change and can be done together with enabling Cosmic by default.