New view containers api has inconsistent naming

[sbatten]

Testing #48407

The new viewsContainers contribution point has inconsistent naming. The expected name appears to be viewsContainers while in a couple places in the code (which gets surfaced to the users confusingly in the debug console) we use viewsContainer. This also permeates inconsistently through the schema interface name viewsContainerSchema and the localization labels within it: ....views.containers...

[sandy081]

@sbatten Good finding.

Regarding schema viewsContainerSchema - it is for single viewsContainer hence it is named like that. There is also schema for viewsContainers while internally refers to viewsContainerSchema`.