kcm: Add visual display number badge next to monitor names
This MR introduces a compact visual badge shown consistently next to every monitor name.
The previous custom implementation (Rectangle + QQC2.Label) has been replaced with the new Kirigami.Badge component. This significantly reduces code duplication, improves maintainability and makes the numbering consistent with the rest of KDE/Plasma.
The badge now appears in the following places:
- Navigation tabs
- Priority reorder dialog
- "Replica of:" combobox items
Display numbers are calculated based on sorted connector names (case-insensitive), starting from 1.
This change significantly improves quick visual identification of displays, especially in multi-monitor setups with identical or similar-looking panels.
Depends on: frameworks/kirigami!1847 (merged)
Edited by Ramil Nurmanov