[vscode] Add viewContainer/title menu as a proposed menu

[rschnekenbu]

New menu was introduced as a proposed menu:

{
key: 'viewContainer/title',
id: MenuId.ViewContainerTitle,
description: localize('view.containerTitle', "The contributed view container title menu"),
proposed: 'contribViewContainerTitle'
},

Task is to implement such menu contribution

[rschnekenbu]

This menu contribution will be either ignore for now, of at least contributes as lower priority. Indeed, vs scode only activates it for now for the debug view container (see microsoft/vscode#212499 (comment) and https://github.com/microsoft/vscode/blob/9bfaf90fb9a479c16c6a33052efb3c9b188f03cb/src/vs/workbench/services/actions/common/menusExtensionPoint.ts#L1062)

[rschnekenbu]

This feature will be ignored for now, as announced in previous comment.