DateTime: Use d2l-localize-behavior

[svanherk]

Switching from app-localize-behavior to d2l-localize-behavior (which wraps app-localize) will achieve 2 things for free:

• Automatic language resolution, so the lang resolution code can go away
• It exposes all of d2l-intl's date/time formatting and parsing APIs, so the dependency on d2l-intl can go away