[vuejs] Add icons to dialog title

[fdaugan]

In dialogs, prepend the title with an icon representing the updated entity.

Generalize this concept to all dialogs of the application

There: http://localhost:5173/ligoj/index.html#/id/user

[Terracosmos]

Generalisation complete across all three repos:

• plugin-id — commit 58489c3 covered the 6 LjDialog instances (User, Group, Company, Delegate, ContainerScope, GroupMembers) and the LigojConfirmDialog action-guards.
• plugin-ui — PR feat(ui): add entity icons to dialog titles plugin-ui#16 (commit 6ea5569) covered the 11 LjDialog instances (Audit, Project, Node, Subscribe wizard, System User/Role/Plugin/Configuration, API Token).
• ligoj host — LoginPromptDialog ships an inline mdi-lock-reset icon, AboutView License modal ships an inline mdi-license icon, VibrantConfirmDialog and LigojConfirmDialog are generic and the plugin callers already pass the entity icon. AgreementDialog is dead code (no usage in the webapp) — tracked separately for removal.

Runtime verified at /id/user (Modifier l'utilisateur dialog): the entity icon now appears in the warm-gradient tile next to the title, exactly as requested.