perf - registerWorkbenchContribution2 and some adoptions

[bpasero]

This adds a new:

registerWorkbenchContribution2<Services extends BrandedService[]>(
  id: string, 
  ctor: IWorkbenchContributionSignature<Services>, 
  instantiation: WorkbenchContributionInstantiation
): void;

getWorkbenchContribution<T extends IWorkbenchContribution>(id: string): T;

with a new WorkbenchContributionInstantiation.Lazy and deprecation of registerWorkbenchContribution.

It follows how editor contributions work and is for #203445

//cc @jrieken