Composition collections in runtime detail view template

[knstvk]

Motivation

Runtime view templates (#5225) generate list/detail views from @DetailViewTemplate metadata, but had a known limitation: composition collections were unsupported — a generated detail view only rendered single-value fields, with no way to view or edit a composition's child rows.

What it does

When a @DetailViewTemplate entity has composition *-to-many properties, the generated detail view now renders a TabSheet:

• the first General tab holds the form of single-value fields;
• each composition collection gets its own tab with a dataGrid (create / edit / remove). Create/edit open the line entity's own detail view in a dialog, so line entities are expected to also carry @DetailViewTemplate.

Entities without composition collections render a plain formLayout exactly as before.

Implementation

• ViewTemplateHelper#getCollectionProperties — returns composition *-to-many properties (associations and datatype collections excluded), honoring excludeProperties.
• detail-template.ftl — adds a fetch-plan entry and a nested <collection> container per composition property, and a conditional <tabSheet>; collection-tab dataGrids use list_create/list_edit/list_remove with openMode=DIALOG.
• Hidden back-reference — the inverse attribute of a composition collection (the child's parent reference) is excluded by default in both the master's columns and the line entity's own detail form (restorable via includeProperties).
• Localized labels — tab labels are emitted as msg:// references so captions resolve per-user at view-load time (the "General" tab uses a new viewTemplate.generalTab key).